You are getting your information from religioustolerance.org??? Are you kidding me? Might I suggest auditing a theology or religious history class at a university and, I don't know, start thinking for yourself.
Look, there has been some brilliant Biblical scholarship over the last 2000 years and it is just sitting, ready for your inquiring mind to discover it. But you are going to an over the top anti-christian site which is ironically titled, "religious tolerance." Look at academic sources and read the Bible through your own eyes.
I have read many of your questions and I can tell that you are very intelligent, you are just very bias, and that bias seems to cloud your understanding of religion. Please, I beg of you, try to look at more scholarly souses, and opposed to popular culture drivel.
ADDITION: What do you mean that where you get the information doesn't matter? For example, It is true, scholars are pretty sure that Marks Gospel, that which is written by Mark, ends as verse 8. This has been known for a very long time. Your sourse says the rest is a forgery, but their is absolutly no historical or literary evidence to suppor that. Most likely Mark died in the middle of his composition, since he was in a prison in Rome, and a close follower finished it. Whats wrong with that? How is that a forgery?
Many of your other issues are most likely copying problems. Keep in mind the printing press wasn't invented till the 16th century. We can all rest assured that some mistakes were made in transcribing the manuscripts.
And finally, you always have translation issues. Because I can read and write ancient Greek, I will tell you many English translations are bad. Some are intentionally so, to promote a specific ideology, but more often than not, its simply because certin Greek words carry a specific connotation not supported in English. The most obvious example of this is "logos" being translated as "word." Logos means so much more in Greek, but their is not real way to translate it. You just need to read Plato.
This is the problem with your source, it assumes something sinister is going on. But there really is no reason to assume the worst, their are far more probable explainations that dont assume a mass conspiracy or religious cover up. Sadly, all my studies in history have really led me to find out that the reality is usually far more simple and dissapointing than mass coverups or mind controle cults.
Finally, why should you attend a thology class or religious history class? Sure, more often than not, they have a pro-religion feel. However, we want you to think for yourself. I would say that your problem is, you are asking yourself the wrong historical questions. You seem to be asking, "How can these Christians believe such stupid things." The problem with this is that you aren't seeking to understand it, you are only seeking to be convinced or not. You should be asking, "Why do these Christians believe such stupid things." This is a much better question because you take your own scepticism out of the equation. You can discover or understand why Christian theology is what it is without needing to accept its validity. History isn't about agreeing with something or not. You dont have to agree with the Romans to understand their culture and empire. All you need to do is ask questions which remove your own emotion from the equation and accept historical charactors for what they are. Who knows, you may find something you respect.