However, your point about when a lot of the New Testament was written is pretty off-base. Paul's writtings were almost all in the form of letters which were shared amongst all of the churches he helped establish. Also, you can tell about the veracity of the things Christ said because of the seperate eyewitness accounts, that while different in overall content, were pretty explicitly similar when Christ spoke.
Christians should use every possible opportunity to witness to the unbeliever, but NEVER pretend that the unbeliever or those who believe in a different "god" are doing an acceptable thing; acceptable to a Christian believer that is.
Paul never met Jesus, not even according to the writings in anybody's version of the Bible. Frankly, I feel that Christianity would have been the better for it, I can't imagine (based on the writings attributed to Jesus) that he would have let Paul carry on in what he had to say about women, gays, etc. All the things that have made problems for Christianity in the modern world. As for eyewitness accounts, certainly there are independent writings of the Roman government at the time that confirm the existance of a historical Jesus, but modern Biblical scholars believe that most of the Gospels, for instance, are copies of third sources. If I do a book report on "A Tale of Two Cities", and you do one, they will not be word for word, but they will have great similarities. Modern Bible scholars have forensic evidence, computer analysis of pre-translated works (from only several centuries after the events were supposed to have happened), and mass communications to help them share ideas on what was said, and what was meant, and even then, they frequently disagree. They understand that bishops in the early centuries after Christianity became aligned with the Roman government did not have these things to guide them in what parts to include in the scriptures, and what parts to burn (and best to burn at the stake those with any memories of a conflicting version, lest it be rewritten some day). If you have a mindset that believes that somehow "God" guided your little tiny sect all through the minefield of human memory and recollection, and saved it from all the misinterpretations that obviously beset your neighbors who believe 99% of what you believe, then I guess its easy to say that the right books were picked by these amateurs sixteen centuries ago.
Sorry, again, got off the point, and that is, I did learn something else about religion on 9/11 and its aftermath. Its that you cannot always tell who's a religious intolerant just by looking for the rag on the head.