When I was a believer I saw the Old Testament as more of a prophetic text and the New Testament as the fulfillment of those prophecies. Eighteen years later as a learned atheist I no longer believe in prophecy of any kind, and have had to rethink my views regarding the old and new testaments of the bible. I remember the days when I relied on what I believed to be the Holy Spirit's guidance in my understanding and interpretation of the scriptures. I got goose bumps when I read a text and had what I believed at the time to be a revelation through the scriptures. I still have those moments but I no longer get goose bumps because I recognize them for what they are; a moment of clarity.
One bad habit that Christians in particular have is that they like to interpret Old Testament scriptures out of context and apply them to their beliefs. They call them fulfilled prophecies of events that allegedly occurred as described in their N.T. scriptures. It has been my contention for years that the fact that the bible is subject to human interpretation is one of many reasons why I don't believe that the book is of divine origin or divinely inspired.
The fact that even among Judaism there are many sects that have arisen from the original form of Judaism as is the case with Christianity is a testament against the church that their book is divine. All of these sects grew out of disagreements on interpretation of texts and doctrines. That there were already divisions in the early church was made evident when Paul was addressing the church of Corinth in Corinthians 1:10,11 10 Brothers, I urge you, in the name of our Lord Jesus
Christ, not to have factions among yourselves but all to be in
agreement in what you profess; so that you are perfectly united in your
beliefs and judgements.11 From what Chloe's people have been telling me about you, brothers, it is clear that there are serious differences among you. (NJB)
As demonstrated above Christianity was already having issues with unity from its beginnings. Today there are around 38,000 Christian denominations in the world! You can read about this and some other facts about Christianity in an article on about.com right here. This contradicts what the author of John claims Jesus allegedly said about the Holy Spirit being the guide to truth to all those who believe in John 16:13,14.
Based on the evidence of religions and their growths and their relativity to ancient mythology, I have come to the conclusion that new religions are created by borrowing from older religions and myths. The Hebrews were influenced heavily by ancient Babylonian, Assyrian, and possibly other myths and since Christianity borrowed from the Hebrew myths they also share some of the same influences. If you think of Jesus as a mythical fabrication then it stands to reason that they would create him as the fulfillment of the previous myths they hoped to supplant.
A careful study of the Old Testament as compared to the New would make it quite apparent that many of the sayings attributed to Jesus were ripped directly from the Old Testament. There is an excellent article on this subject that deals with the historicity of Jesus right here. Be warned though! This article is very thorough and pretty long so read it carefully and take your time with it. In fact it's in two parts, so when you are done with the first part you can find the link to the second part right on the page itself.
In the end the New Testament as the Old and other former religions are nothing more than a conglomeration of ancient plagiarized myths. I would not be surprised if long after I'm gone Christianity becomes a thing of the past and is subsequently supplanted by a new religion.
In closing, this article demonstrates clearly that myths/religions simply build upon one another and like all things change and evolve according to the culture into which they are introduced. Religion is a creation of man, thus gods are a creation of men, and like men they are subject to change. There is nothing divine about the process.