The Five Fundamentals below are provided courtesy of European American Evangelistic Crusades. Fundamentalist Christians believe that in order to be a true Christian, one must believe all five:
There are five fundamentals of the faith which are essential for Christianity, and upon which we agree:
1. The Deity of our Lord Jesus Christ (John 1:1; John 20:28; Hebrews 1:8-9).
2. The Virgin Birth (Isaiah 7:14; Matthew 1:23; Luke 1:27).
3. The Blood Atonement (Acts 20:28; Romans 3:25, 5:9; Ephesians 1:7; Hebrews 9:12-14).
4. The Bodily Resurrection (Luke 24:36-46; 1 Corinthians 15:1-4, 15:14-15).
5. The inerrancy of the scriptures themselves (Psalms 12:6-7; Romans 15:4; 2 Timothy 3:16-17; 2 Peter 1:20).
And those who disagree with any of the above doctrines are not Christians at all. Rather, they are the true heretics. So disagreements are perfectly acceptable within the confines of Christianity, because our salvation does not hinge upon doctrines other than the above five.
But if some deny even one of the five fundamentals mentioned above, they have departed from the faith, "giving heed to seducing spirits, and doctrines of devils" (1 Timothy 4:1). By denying the above scriptural doctrines, they have heaped to themselves "teachers, having itching ears" (2 Timothy 4:3); thereby even "denying the Lord that bought them" (2 Peter 2:1). These are the true heretics, who are preaching "another Jesus", according to 2 Corinthians 11:4:
For if he that cometh preacheth another Jesus, whom we have not preached, or if ye receive another spirit, which ye have not received, or another gospel, which ye have not accepted, ye might well bear with him.
And later in this same chapter, Paul refers to these people as the ministers of Satan, in 2 Corinthians 11:13-15: For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ. And no marvel; for Satan himself is transformed into an angel of light. Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.
So, please - if you take offense to differences in lesser doctrines, don't think that we are condemning you as unbelievers or heretics. Nothing could be further from the truth. As long as you hold to the five fundamentals of the faith, you may join the debate. And together, we shall reprove the unfruitful works of darkness (Ephesians 5:11).