The bible is indeed based on alot of letters, but my problem with those letters are, that they are written in a time where people had an entirely different perception of events....
This doesn't seem to make sense to me. You are saying that people in ancient history where irrational and unable to accurately understand the things they saw around themselves. This might have been true for other things but when it came to worshiping God, the Jewish people really knew what they where doing, it was based on many generations of tradition and teachings.
So if the letters of the New Testament are regarded as written by the early Christian witnesses to the Resurrection and if this is accepted by the early Christian Churches as guidance to the Christian faith, we have to measure why was this acceptance made?
Ancient Jews where extremely particular and detailed when it came to worshiping God, they treated it probably with more importance than what they do nowadays with all "modern day" factors to distract us. So what is written in the New Testament it is not just made up stuff written by some random person and believed by a few random other people who then encouraged others to do the same. The structure required for a revolutionary change in the ancient Jewish religious tradition just wouldn't work if the Jews where regarding random bits of made up letters to give them guidance. In fact the letters are ground breaking in lessons in morality and spiritual guidance all which use the teachings of Jesus as the source and source for elaboration through the Old testament.
If you compare the Old Testament to the New you will find similarity and contrasts. The thing is that the New Testament letters talk about no longer a religion of works or following a Law for salvation, but rather a submission to guilt and an acceptance of your guilt to be dealt with through the sacrifice of Christ. But the New Testament does not do away with the Law, it re-enforces it but highlights we should not longer believe that we put ourselves right with God but following his Law but by upholding it and agreeing with it and understanding how we break our connection from God continuously, how we deal with our sin instead of trying to forget about it by continually and really hopelessly trying to follow a perfect model we will never alway maintain.
Secondly, few people could write in those days so its very much possible that dozens of people had to tell each other a story before it was actually written down, and you know what happens with stories with this treatment :p
This is not actually true. If you see what was written historically about Christ and the belief of the Resurrection it was written close to second hand and even third hand accounts of the Ressurection. Some older historical documents are written when there are even first hand witnesses to the resurrection! This is to say a lot if you study ancient history. A lot of accepted facts about history of all countries are based on accounts written 100's of years after the fact.
So it is futile to say that what is written in the Bible is all stories and mutated and corrupted. Even if things are changed, even if 50% of the bible is altered, it is impossible to destroy the message of the bible because we can measure teachings in multiple sections.
Let me give you one very brief example of how to measure what we read and how the bible texts have been corrupted. When Christ was dying on the cross one of the criminals who also was being crucified along side him asked Christ if he would essential go to Heaven. Christ responded with something along the lines of "I tell you, today you will be along side me in heaven."
Now some Christians have misinterpreted this to mean that the man was going to go to
heaven at the moment he died. This is a major misinterpretation and it is caused by the fact that a comma has been put in erroneously for the English translation, you will of course find no such punctuation in ancient Hebrew or Greek texts. It should read, I tell you today you will be ....... However Christians who study the bible will not be confused by this error, simply because we can see that Christ spoke often with the words, I tell you today etc. It was a way of expression back then, if we understand the historical context of what was being said we will not be confused, and we are shown obviously other times where this expression is being used in the bible.
But what happens if we are talking about words that have been changed? Certainly some words changed from Ancient texts to English. The characters for Raven in ancient Hebrew can mean up to 5 things for instance

But the way in which the bible is written leaves no room for misinterpretation even if certain words are altered because how it is written reflects a pattern of knowledge, each which effects the other. I could almost describe it as a mathematics book in the way it so accurately orders the knowledge written in it.
In my own personal journey studying the bible i find seeing patterns in the teachings very rewarding to my understanding of the doctrines of Christianity. However Christianity is quite simple, all there is to it is Love that is the greatest commandment, but there is also the side of Christianity which will satisfy those who want to pick it apart and investigate every aspect of it. I have always done this with a neutral stance, it is useless to be bias when you research things
So if you are scared that everything in the Bible is made up then I would ask you to research who where the people who wrote the books in the New Testament. What historical evidence is there of them of actual have lived. This would require that you research others mentioning these people and it would then require you to research if what these people are saying can be believed or not. This sets you up with some work, and perhaps even you should read up on the method to study Ancient history before you try to research the history of the Bible. I would really suggest you read books concerning the historical reliability of the bible.
Thirdly, our catholic 'holy' friends in the dark ages had the tendency to change the bible as much as they pleased, as long as they were able to get richer.
All of which the Catholic church changed has been revealed to regard issues regarding hierarchy of power, they misinterpreted the bible more than changing what was written in the bible though. It is how they managed to institute a Pope as a human leader to all Roman Catholics, something which the Bible never taught should be done. How Catholics can call him and other priests Father, where the bible says that God is the only one that could be called Father. It all has to do with power control of the mass, it however does not change anything of the main teachings of Christianity, it all is essentially there. I would be confident to say that if 51% (which is ridiculous if it is a fact, it is more like 99% of the bible is maintained) of it was there it would still be accurate enough because we can verify what we read through other texts
Even though the Catholics change things it all has been revealed and nowadays we have no excuse to say we can't study the bible because this group has change this or that. Everything that has been changed in the Bible has been documented and revealed for all to see! So if you mindlessly dive into say the Book of Mormon as truth research the history of where it came from, what evidence was given, you will find everything there is shrouded in mystery and there are no witnesses, nor any evidence of the tribes it talks of, nor any trace or witness to the tablets the books where written on etc.
The bible however is a completely different matter. If you now try to scrutinize its historical accuracy and relevance you will find you have task. All tribes mentioned in the bible can be found, there are so many places in the bible that can be found today, there are historical facts of Jewish history written in the Bible which can be verified by other non-biblical accounts of Jewish History. Jesus Christ can be found all over the place mentioned by all sorts of non-Christian ancient historians. These people wouldn't just listen to stories from one person they would actually look into things, they where professionals in their field of recording history, they where the academics of the time. They where not just some random person pulled from the street and asked to write whatever story they had heard, but this is the stupid belief some people who do not look into the facts actually believe.
Why do people believe in ancient roman history but selectively not the ancient history of the Jews regarding Christ? It is an obvious choice to ignore it! We can put all sorts of smokes and mirrors around us to deny this fact, but people are literally by choice saying, right there is evidence that Christ lived there is this evidence that he rose from the dead, I think its too hard to believe it is true because I will have to change a lot of things, humans being inherently lazy will take the easy path and simply deny and put up all sorts of doubts which give them the excuse to simply sit back and shrug their shoulders at the facts.
Yeh, people have been put away with other types of evidence and later found to be innocent.
This is true but has little relevance when it comes to testing the evidence for Christ. Sure people are put away and found to be innocent, Jesus was found to have existed and 2000 years later still found to existed. Much more time has passed to scrutinize if Christ really existed and rose from the dead.