Considering the fact that there are literally about 35,000-45,000 Christian orgnizations or sects around the world. It is quite obvious that believers don't seem to agree on what it is that their so called holy book actually says about God and many other things. This is mostly due to hermeneutics (methods of interpretation). The most commonly used methods are the literal and allegorical methods of interpretation.That being said here are some common points of contention amongst Christian denominations.
1. The trinity: Some believe that God is somehow manifested as three separate entities; the father, the son, and the Holy Spirit. Some churches reject the idea of the trinity altogether while others regard the whole matter a mystery that somehow we cannot fully comprehend or know. I personally believed that the three were separate entities but that they were one in plan and purpose.
2. Baptism: Some churches baptize children while others don't believe that children should be baptized till they reach the so called age of accountability where they can conciously choose to worship God through accepting Christ as their Lord and saviour. Other churches only baptize older kids and adults and believe that if a child is not capable of making a decision for Christ and dies that he/she will automatically be saved through God's grace.
3. Miracles: Not all churches accept the idea of God working miracles through his believers as he allegedly did in the Bible through his disciples. Some believe that the miracles were only necessary to establish the church and that once that had been accomplished that they were no longer necessary.
4. Idols: Many protestant churches don't believe in the so called veneration of idols and they equate it with idolatry. Catholics call it veneration but many Catholics I know of actually pray to these idols for favors etc. I personally think that it is nothing more than idol worship and that it is clearly condemned in the scriptures.
5. Creation story: Depending on which church you belong to and what denomination they represent you will find that some consider the creation story to be allegorical and not a literal and actual historic event.
6.Adam and eve: Were the first pair according to the scriptures actual historical figures or were they fictional? I personally believe that the author or authors of the narrative believed that they were literally historical figures. Adam is given an age of death and a geneology why would someone do this if they were not historical figures? Also, the author of Romans and other New Testament writers also believed in a literal Adam. "Therefore, just as sin entered the world through one man, and death
through sin, and in this way death came to all people, because all
sinned--" Romans 5:12
7. Paradise: Some believe that paradise will be here on a renewed earth after the so called tribulation and judgement. Others believe in an eternal abode in some heavenly spiritual realm.
8. Predestination: Some believe that not everyone will be saved that some are predestined to salvation while others are not. Others believe that salvation depends on your acceptance of Christ and faith in his redeeming act. The latter believe that everyone has an equal opportunity of being saved.
9. Faith: Some believe that all you have to have is faith to be saved while others believe that faith is just one part of salvation. They believe that you have to also do good works and make some life changes that reflect what you believe.
10. The rapture: Some believe that we will all be caught up into heaven literally. Others believe that the verses referring to the rapture are not to be taken literally.
11. The resurrection: Some believe that Jesus rose from the dead bodily (physically) while others believe it was a spiritual resurrection.
These are just some of the many contentions that believers have about the scriptures and what they mean. Religionfacts.com has a nice list of some of the more common Christian churches and what they believe here.
Notes: Biblial citations are taken from the New International Version of the scriptuires. All other citations have been hyper linked in the text itself.