Center for Biblical Theology and Eschatology

The Reasons for Sexual Purity

by Rev. Carl Haak

Dear radio friends,

I ask that you take out your Bible today and turn with me to I Thessalonians 4:3-8. The church father Augustine, in his Confessions, explains at length his battle against the lust of sexual sin. Augustine’s Confessions, by the way, is a book well worth your obtaining and your reading. He writes there that so great was this sin to him that he found himself praying to God, “Give me chastity, but not yet.” The deceit and promises of fornication and adultery held tenaciously to his flesh. It was only the grace of God in God’s Word which gave him release. He explains, in his Confessions,that it was while reading from Romans 13:13, 14 that the Spirit of God worked mightily in him. “But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof.”

The war against the lusts of sexual sin is serious and difficult and sobering and real to the child of God. It is real for youth, real for adults, real for the married, and real for children – for all of us. That is true, we say, because of the world in which we live. And there is, of course, truth in that statement. The very idea of sexual fidelity and faithfulness in marriage, the very idea of purity in single life, the very idea that the sexual union belongs exclusively in marriage and that marriage is a lifelong bond – these thoughts are trashed. Biblical purity is an offense to this world, and the world does its utmost to stamp it out. That is because the world despises God. Make no mistake, the delight and the acceptance of what the Bible calls uncleanness is only a symptom. The apostle Paul puts his finger on the problem in verse 8 of I Thessalonians 4: “He therefore that despiseth, despiseth not man, but God.” The sexual perversity of our society is not a revolution against previously held morals. It is a revolution against God! It is a despising of God Himself.

But, you see, the world in which we live is no excuse for us because the Bible shows us that our problem is not first of all the world in which we live. But the problem is, first of all, ourselves and our sinful flesh. The problem does not begin outside of ourselves in pornography, magazines, X-rated movies, the Internet, or the woman next door, but within. We read in the Scriptures, Matthew 15:19, 20, “For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies: These are the things which defile a man.” And that is the concern of God, first of all, within. There is only one power to subdue that. That is the grace of God. Where the grace of God has created that difference, then there will be the desire to be sexually pure – the desire of David in Psalm 51, the psalm of repentance over his sin of murder and adultery, when he said, “Wash me clean within.”

What is the will of God, then, for you? For you, whom He has purchased in the blood of His Son, and who, by grace, confess Him? What is the will of God for you as a young person? What is the will of God for you as a child, eleven, twelve, thirteen? What is the will of God for you as an adult – as a married person? The will of God for you is sexual purity.

In the day of the apostle Paul, the Christian saints in Thessalonica, as well as in Corinth and Philippi, lived in the Greek/Roman culture which not only practiced every form of sexual immorality, but deified it, made it a God. The apostle says in verse 5 of I Thessalonians 4 that we are to live “not in the lust of concupiscence, even as the Gentiles which know not God.” You see, not only was fornication, pornography, and all uncleanness readily available in the city of Thessalonica where the Christians lived, but, for the heathen, it was considered a sacred duty, it was considered an act of worship for their gods. The Greek and Roman temples were staffed with prostitutes. Imagine the temptation and the pressure upon the young converts of Christianity coming out of such a life. The apostle, therefore, speaks bluntly to young people, to men and women of his day, and he says, “This is the will of God – not that you be conformed to this world, but that you be “transformed by the renewing of your mind, that you may prove what is that good, and acceptable, and perfect, will of God” (Rom. 12:2). This is the will of God: your sexual purity.

You see, the true gospel of Jesus Christ did not compromise. It did not adjust itself to culture; it did not begin to philosophize with culture and talk about sexual preferences and all the rest. The church of the apostle’s day did not form committees to investigate sexual tendencies. But the gospel was glorious. For the gospel planted the cross right in the middle of a person’s life and said, “The body is not for fornication, but for the Lord; and the Lord for the body” (I Cor. 6:13).

We read in this book of I Thessalonians that the Thessalonian Christians were characterized by an eager anticipation of the return of Jesus Christ. In this paragraph (vv. 3-8), the apostle teaches us that our hope of the world to come must not make us forgetful of the importance of this present life. We must have our lives in line now with the life which shall be ours. There must be no inconsistencies. That means that it must be a life which is pleasing to God. I Thessalonians 4:1, “Furthermore then we beseech you, brethren, and exhort you by the Lord Jesus, that as ye have received of us how ye ought to walk and to please God, so ye would abound more and more.” The Christian life is not simply that we have a view of eternal salvation and do not concern ourselves with the present life. The Christian does not live with a view to obtaining the maximum amount of satisfaction for himself in this life and then also anticipate the maximum amount of satisfaction in heaven. But the Christian lives his life right now to please God!

Then, he says in verse 2, “for ye know what commandments we gave you by the Lord Jesus.” The word “commandments” there is a military term. It is orders, the charge, given by the commander to the troops. Christ issues orders to us who are upon the earth. He is the great leader, the champion of our salvation, and He issues orders to us in the battle of faith for our deployment, for our obedience.

You see, it does not belong to us to make decisions as to how we are going to serve God: whether we are going to be obedient and live after holiness or whether we are not. The Christian does not say, “Well, holiness is a good idea, but in this circumstance it does not really help.” No, the Christian lives his life this way, “I am the servant of God. The Lord lays upon me His will.”

What is His will? His will is your sexual purity. “For this is the will of God, even your sanctification, that ye should abstain from fornication” (v. 3). Let that sink down. “For this is the will of God.” The will of God in the Scriptures is, first of all, God’s eternal purpose, that is, what God planned before He created the world – what the Bible calls God’s good pleasure. Ephesians 1 is a commentary on the will of God. We read there that before the foundation of the world, before God created, He chose us in Christ – “Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will.” So, from eternity God chose to save a people in Christ for the glory of His name. What was His will for these people? God predestinated us to be chosen in Christ, to be the adopted children of God. For what purpose? We read in Ephesians 1, “That we should be holy and without blame before him in love.” This is the will of God, says the apostle – your sanctification. That you be holy. The word “sanctification” is “to be made holy” by the Spirit of Christ given in your heart. God’s purpose in His election of eternal grace, God’s purpose in the redemption in the blood of His Son, was that we be a people who are holy, separate from the world, consecrated unto Him in love.

Now the will of God also refers to God’s command. It is God’s eternal purpose, yes. But it is also His will in the sense of command. For He is God, He is the Lord. We have been purchased in the blood of Christ. Therefore, His will is our command, our delight. What is that will? His will is our sanctification.

Sanctification, as I said, means to be made holy, the work of God in us by which we are made dedicated to God in love. One of the simplest and clearest explanations of sanctification is given in Galatians 4:19. There we hear Paul saying to the Galatian believers, “My little children, of whom I travail in birth again until Christ be formed in you.” Christ formed in me. That is sanctification. That was the holy passion of the apostle Paul. Is it yours? My thoughts, desires, goals, interests, time, friends, attitudes, words – all to be like Him … that Christ might be seen in me.

Christ formed in me. That is sanctification.
What is the will of God for you? What was the purpose that God had in mind when the Son of God was given to bleed upon the cross for your sins? What commandment does He now bring to you in your life? Sanctification – that you be holy in your life – that Christ be formed in you. That is the will of God for you.

Sometimes we ask the question, “What does God want in me, what is His will for me?” Have you ever asked that question? Maybe as a young girl you ask, “Does God want me to be an oddball at the school, made fun of, a social outcast, unaccepted?” The answer is, If all of that comes to you in the way of obedience to your God and a desire to be pure, chaste, and holy, then the answer is, Yes, that is what God wants.

You ask the question, “Does God want me to be single?” If the young man or the young woman you put your eye on is not godly, then the answer is, Yes, at least for now. That is the will of God.

You ask the question as a man, “Does God want me to pass up this promotion? What is the will of God? What an opportunity, what an advancement in my work! Does God want me to live still in a two-bedroom house with these bunk beds for the kids?” Here is the answer: If that promotion comes at the expense of obedience, if the advanced income comes at the expense of obedience to God and at the expense of your wife being home with your little children, then the answer is, Yes. God wants you to live in that two-bedroom house with those bunk beds.

You ask the question, “Why does God send this trial into my life, this struggle, this thorn? Why? Why this sickness that is affecting my whole family, our whole life? Why the sickness of my child? Why does it have to be this way?” The answer: Your sanctification – that you be holy, that God work in you a beauty of holiness.

Specifically, the apostle says that the will of God is our sexual purity. For the apostle works it out and says, “This is the will of God, even your sanctification, that ye should abstain from fornication.”

The word “fornication” here refers to any form of sexual uncleanness. Usually, in Scripture, it is a word which refers to sexual activity outside of a marriage covenant. Fornication is the arousal of sexual desires outside of a marriage bond. It may be the heavy petting, the touching, the leading to arousal of sexual desires. It is looking at a pornographic magazine. It is the suggestive talk. It is the jokes, the innuendoes about sexual uncleanness. Fornication is any kind of unmarried fooling around. You know what I am referring to. We must be warned in the Word of God. We must be warned in the recent national scandal concerning this that we too can become technicians of language, saying that all that matters is, well, what does “is” mean. We can invent arbitrary rules for ourselves to allow for some things and not for others, to draw our own lines for how far we can go, for what really is base and sinful.

God’s Word is straight, and blunt. The intention of arousal of sexual desires outside of one’s wife or husband is fornication, is uncleanness, is sin. Abstain from fornication, says the apostle. That is the will of God. The word “abstain” means, “don’t play,” “don’t tantalize,” “abstain,” “hold yourself back from.” For instance, we read in I Thessalonians 5:22, “Abstain from all appearance of evil.” Acts 15:29, “Abstain from meats offered to idols, and from blood, and from things strangled, and from fornication.” To hold oneself. That is what the word means. It means that the calling of the child of God is to see himself as one who belongs to the Lord, and when pulled away from the Lord by lust, to hold by faith to the integrity and to the purity that is his in Christ.

We read in I Corinthians 6, “Now the body is not for fornication, but for the Lord, and the Lord for the body.” Abstain is the conscious walk of faith. It is a faith which says, “I am His.” Virtue is not cowardice. Virtue is courage. Virtue is not, “What if someone finds out in the church, what if I’m caught?” Virtue is not that. It is faith, faith in God, in Christ. Faith says, “In Christ I have a great good, I have a precious thing. I belong to Him. My body is the Lord’s temple. It is not Satan’s pornography center. My body belongs to the Lord and to my wife or husband. I hold it in honor.”

The apostle goes on. He begins to apply the will of God concerning sex to marriage. In verses 4 and 5, “That every one of you should know how to possess his vessel in sanctification and honour; not in the lust of concupiscence, even as the Gentiles which know not God.” I say that the apostle is speaking there about marriage. When he refers to vessel in verse 4, he is referring to the wife. That becomes very plain when we see, first of all, that the translation should read this way: “That every one of you should know how to take his vessel.” Often the Scriptures refer to a man who “takes to himself a wife.” Paul is not talking about how one views his own body as the vessel of God. That is true. But he is referring to how a man conducts himself towards his wife, the vessel that God has given. We read, for instance, in I Peter 3:7, “Likewise, ye husbands, dwell with them according to knowledge, giving honour unto the wife, as unto the weaker vessel.”

The Bible says that the wife and the husband are vessels intended one for the other. What is the will of God for our life? The will of God is that we live in marriage in purity (Heb. 13:4): “Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge.” Here the Word of God is telling us how we should marry and how we should live in marriage. The Word of God is telling us that there is a right way and there is a wrong way to view your wife. You must not view her in the lust of concupiscence, even as the Gentiles which know not God. That was verse 5. The lust of concupiscence refers to the passion of overwhelming desire. The apostle says: The Gentiles, the heathen, apart from God, how do they view their wives? They view them in terms of what they want, when they want it, in terms of themselves and of their pleasure. The wife is simply an object to satisfy their own passions and their lusts.

Rather, says the apostle, you must view your wife in sanctification and honor. It means that you view your wife as Christ views the church and gave Himself for her. You honor her, value her, know her worth. Honor your wife as the gift of God given to you to nurture and to cherish. Delight yourself in her. That is your calling. That is the will of God for you in marriage – to honor your wife.

Who is going to teach these things to your sons? The world? The world is very blunt and very bold in teaching them to view women in the lusts of concupiscence, in the passion of overwhelming desire. Who is going to teach them? That is your calling, husbands.

Young men, are you ready for marriage? Are you ready to receive a wife in sanctification and honor? What is there different about you as a young man? The Christian father, hopefully, is going to ask you, is going to say, “I don’t want my daughter with just any young man.” What is there different about you? This is the will of God for you: sexual purity.

The Word of God there teaches that God’s will for the child of God is sexual purity. That will is that we be sanctified. “For this is the will of God, even your sanctification” (v. 3). Then, applying it to a specific area of our life, “That ye should abstain from fornication.”

The Word of God there continues to say that this applies to marriage. Everyone who is married must know how to possess his vessel in sanctification and honor, not in the lust of concupiscence, not in a passion of overwhelming desire as the Gentiles or heathen who know not God.

The will of God, then, is purity – in single life and in married life. And the will of God for those whom He has purchased in the blood of Jesus Christ is also faithfulness in this. For, we read in verse 6, “That no man go beyond and defraud his brother in any matter,” or, literally, “in this matter.” One must not go beyond, must not overreach, defraud, deceive. The apostle is referring to adultery, which is the violation of the right of another, whether that is fornication and one robs another of virginity, or whether that is another man’s wife or another woman’s husband. Do not overreach, do not deceive, do not disregard the bounds of a brother’s marriage – what the world calls “an affair.” Some say, “We were meant for each other,” and “We must seek our own happiness, therefore we may engage in sexual activity outside of the bond of marriage.” No, the Word of God says that we must not do that. That is sin. Building on the truth of the sanctify of marriage and of the exclusiveness of that bond, we must live with our husband or wife in the bond of marriage in holiness and in honor. That is the will of God. You may not involve yourself in the union that belongs exclusively to the brother’s marriage. You may not have your brother’s wife. You may not lust after her in your heart.

We read in Proverbs 5:15-20, “Drink waters out of thine own cistern, and running waters out of thine own well…. Rejoice with the wife of thy youth…. Why wilt thou, my son, be ravished with a strange woman, and embrace the bosom of a stranger?”

What is God’s will, then?

Abstain from fornication, all sexual uncleanness.

Live in marriage in sanctification and honor.

Do not cast your eye towards your brother’s wife.

That is the will of God for us.

Why? Why is this so important?

The passage from which I read (I Thess. 4), in the second part of verse 6 and also in verse 8, supplies reasons for the Christian’s sexual purity. There are three of them. Let us consider them.

First of all, “because the Lord is the avenger of all such, as we also have forewarned you and testified.” The apostle there is saying that the Lord is the avenger of all such. All such what? Of fornicators. Of those who take a wife out of mere human lust. Of those who disregard the bounds of the brother’s marriage. Even if the brother would never figure it out, never get wind of it, God is the avenger of all such. Even if these sins remain covered, God remains the avenger of all such sexual impurity. The word “avenger” refers to someone who sets right the wrong, one who administers justice. The Lord created marriage. The Lord created the human body. He gave to marriage the gift of sexual union. He created it good and for His own purpose. And He will take action when it is perverted. The apostle says, “The Lord is the avenger of all such sins as we have also forewarned you and testified.” We warned you about this before and we testified most solemnly in the presence of God.

For example, I Corinthians 6:9, 10, “Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God.” The Bible makes it very plain: the grace of God, working in the Christian, is a grace which calls him to depart from every way of sexual immorality and to walk in a way of genuine repentance. The apostle goes on in I Corinthians 6:11, “And such were some of you: but ye are washed, but ye are sanctified (made holy), but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.”

The Christian walks in sexual purity, first of all, because he knows that God is the avenger, God is the judge of this sin and He will take action. Though we rejoice as children of God that the judgment that we deserve also for this sin is removed in the blood of Christ, nevertheless, the thought of God’s hatred of this sin is also a reason for the child of God to flee from it. I do not want those judgments of God in my life, or in the life of my family. I do not want to come under the chastening of God in this area of life, for these chastisements of the living God are some of the heaviest known. It is not so that fornication is harmless. It is not so that it is neutral, leaving no effects upon a person’s life. This is the deceit and the lie of the devil himself. It is not reality, it is not true. It is not so that fornication is simply something to be expected, an inevitable part of a person’s life – part of being human. No, the Bible says that fornication is a sword going down through the bones and piercing one’s soul with untold sorrows.

The pleasures of fornication and sexual uncleanness are deceit. They are lies. They offer something they cannot give. They offer satisfaction. Only obedience and only the life of God can give that. In reality, the way of uncleanness gives dissatisfaction.

That is especially true of this sin. It cannot satisfy, so one must go deeper and deeper into this sin. Men and women who blindly fall into this sin discover that God is not the frail deity our society assumes that He is. They discover that the God of the Bible judges the sin of fornication in one’s lifetime and at the end of one’s life.

He judges it in one’s lifetime. He visits a man with sexual diseases, conflict, guilt, turmoil, lack of peace. It makes the soul empty, miserable. And at the end God judges, too. He closes the gates of everlasting fire in the face of those who did not repent of their fornications ( Rev. 16).

A second reason for the Christian’s sexual purity is stated in verse 7: “For God hath not called us unto uncleanness, but unto holiness.” The call is God’s saving call. It is the voice of God heard in the soul and in the heart saying, “You are Mine, come to Me.” Do you hear that call? That is the work of the Spirit.

God calls us not to uncleanness but to holiness. We have been called out of sin, called out of the world into the light of light. God is saying to us, “Take stock of who you are.” Consider carefully what God has done for you. Do not leave all of the Christian doctrines and truths in a notebook on your table. Do not leave it within the covers of your Bible. But, by prayer, let it sink down into your soul in order that you might know how to view yourself. “I am called of God to holiness. I have been made pure in Christ. I am one who is called to serve Him by presenting my body a living sacrifice of praise and obedience to Him.” That is dignity, honor, beauty, joy!

Honor and beauty and joy is not compromising yourself in dress so that you turn heads. Honor, dignity, joy, and beauty is not that some boy shows attention to you. It is not found in being suave and seeing how many girls you can get. Dignity, honor, worth, beauty – these are the things Christ alone can give. And He has called me, called me unto Himself, to walk in these things. Learn the gospel. Make the gospel personal to yourself by faith. Read, study Scripture. Learn of God’s purpose in redemption. Put yourself in the yoke of Christ. Get into the spiritual gymnasium and build that Christian character. And learn. Learn to run away. Learn to take God’s warning seriously.

The third reason for the Christian’s sexual purity is stated in verse 8, “He therefore that despiseth, despiseth not man, but God, who hath also given unto us his holy Spirit.” “Despise” is a word which means to make null and void. The idea of “to despise” is to make of no importance. To despise means that one would say that this will of God for sexual purity has no importance. The world does that. Unbelievers think that the sexual act is just another physical act – something like scratching themselves when they are itchy or drinking water when they are thirsty. They despise sexual purity. They make themselves as beasts. They say, “It’s all a man’s code, so we can set it aside and make it null to suit us.”

But the Word of God says it is much more than that. It is to despise God – God the Ccreator, the One to whom man is answerable, the One who has made the human body for Himself. Unbelief thinks that God can be set aside, that God can be despised, that God can be ignored. But this is not so. For God will judge. And He knows what to do when a man shows contempt for Him.

There is a very powerful passage in the Word of God that I’d like to read with you from Psalm 50, especially the last verses of the psalm. In this psalm God has declared Himself as the glorious God who owes His life to nothing outside of Himself. Then, in verses 16ff., He tells the wicked in the way of sin that He sees every action of sin. He goes on to expose the self-thought of sin – what a person is thinking in the way of sin. God knows what a person is thinking. “These things hast thou done (these acts of transgression), and I kept silence; thou thoughtest that I was altogether such an one as thyself.” In the way of sin, one is thinking that God is like himself. As human beings our power is limited. As human beings we change. One thing is important one day; two years from now it is not very important. “Thou thoughtest I was like thyself. Your thoughts of Me were human,” says God. “But I will reprove thee and set them in order before thine eyes. Now consider this, ye that forget God, lest I tear you in pieces,” says the psalmist, “and there be none to deliver. Whoso offereth praise glorifieth me: and to him that ordereth his conversation aright will I shew the salvation of God.” God is not like man. God is the pure, God is the holy One, and God is the avenger of all uncleanness. God will judge. God will maintain His own holiness.

Our flesh would make this will of God for purity null and void. Our flesh would foolishly want to break the bounds that God has set and ensnare ourselves in ruin and misery.

Then the Word of God says, “You are not simply breaking a human code.” We are sinning against God who is present at that moment. That is what the apostle means when he says “God hath given unto us his holy Spirit.” He has given us the Spirit to dwell with us. He is present. He is present at that moment of sin. He is there. Our bodies are not ours. They are purchased with the blood of Christ. Not only does the body belong to Him but, by the grace of God, He dwells in us by His Holy Spirit. He has given the Holy Spirit to us so that we are not only His property and then left vacated, but God dwells within us. Right now, God dwells in me. He dwells in you, as a child of God. He dwells in us by the Holy Spirit.

Can I? May I? Will I give that body over to sexual lust? The mind to uncleanness? The deeds of the body to sin? God forbid it me!! Do you know that?

When I ask, “Do you know that,” I am not simply asking if there is an apprehension of what I said, an understanding intellectually of what I said. That is not what I am asking. Do you know, as a living truth in your soul, that you are purchased by the blood of Jesus Christ, so that the words “Christ” and “cross” are not mere words but reality? And do you know that the Holy Spirit dwells within you, not merely as a textbook answer, but as the reality of your life, Christ in you, the hope of glory (Col. 1:28)? Do you know that? That is why you must be sexually pure, because Christ dwells in you.

Then you know the honor and dignity of your body as the temple of the Holy Spirit. But then you also know something more: you know the joy and the goodness of purity.

We have a gracious Savior who wipes away the mountain of our filth, who restores us again. We have a faithful Shepherd, we who stray foolishly into the devil’s den, we who play with eternal ruin and misery. The Shepherd restores us again and brings us back to Himself. Sometimes that way of restoration is painful, extremely painful. But it is the Shepherd’s way of bringing us back to what is right – the way of truth, righteousness, and purity.

This is God’s will for you. No matter what the world will say, no matter what your flesh is telling you, no matter how strong your urges may be, this is the will of God: sexual purity for you as a young person. For you as a child. For you married, husband and wife. For you who are single. Sexual purity. This glorifies Him. And when His will is our delight, then truly God is glorified in you and Christ is seen in you.

May God so grant to us.

Let us pray.

Father, we thank Thee for Thy word. We thank Thee for our Savior. We thank Thee, O Lord, that Thy word is clear to us. Work its power in our soul. Give us to see the foul vileness of sexual immorality and give us to taste and rejoice in the purity of the love of God. In His name do we pray,


Rev. Carl Haak graduated from the Protestant Reformed Seminary in June of 1979 and was ordained into the ministry in September, 1979 as pastor of Southeast Protestant Reformed Church of Grand Rapids, MI. In 1986 he accepted the call to serve as pastor of the Lynden Protestant Reformed Church of Lynden, Washington. In 1994 he began serving Bethel Protestant Reformed Church of Roselle, Illinois. In 2004 he accepted the call to the Georgetown Protestant Reformed Church; Hudsonville, MI. He also serves as the radio pastor of the Reformed Witness Hour. This article first appeared as a two part series on the Reformed Witness Hour on November 12, 2000.

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