Scotty,
Welcome to MR and I sincerely thank you for your very good question. This has been a question that has been on my mind for years.
IMHO Premillennialism is NOT a simple mistake but a major error in hermeneutics, which can lead to serious errors in many other doctrines. I will list a few of the errors:
1. Your understanding of National Israel.
2. Your understanding of the Bema and White Throne judgment.
3. Your understanding of the Anti-Christ
4. Your understanding of Rewards in heaven
5. Your understanding of the resurrection (2 or 3)
6. Your understanding of the 1000 year reign.
7. Your understanding of Heaven and the life hereafter
8. Your understanding of the way of Salvation (1. 2 or 3 ways)
9. Your understanding of the age of accountability
10. Your understanding of all Jews eventually being saved
11. Your understanding of the Carnal Christian
12. Your understanding of the secret return of Christ
13. Your understanding of Second Chance Theology
14. Your understanding of the spiritualized Scriptures of the Bible.
Perhaps there are more and you can add to this list. We can see that it affects more than a one simple misunderstanding of God and His Word.
Historical Premillennialism avoids many of these mistakes which might make it a non-essential but Dispensational Premillennialism which directly affects God’s Salvation Plan, puts it into the heretical category. Many, otherwise good, Premillennialism Pastors, cannot help but let this doctrine leak into their sermons. Therefore, I will not listen to or attend one of these churches, no more than I would listen to a Mormon, JW or other cult. Mountain Retreat is a good place to study, if you can avoid those with non-biblical or political comments and opinions.
Bill