The early church used most of the books in the canon we use today. Also, almost the entire NT can be reconstructed from quotations of and references to it by the church fathers. The OT was considered scripture by Jesus. The NT was written by apostles or those who were with apostles (although the writer of Hebrews is unknown).
This article, which is only one page, gives some good general apologetics for the Bible as God's word:
Here's another brief article on why we can believe the Bible is God's word:
http://www.faithfacts.org/search-for-truth/questions-of-christians/is-the-bible-really-gods-word
One of the arguments it makes, which I have heard before, is that why would man produce a book that makes man look so bad and helpless in their sin? It's a good point.
I was saved while reading God's word (although God intervened several months earlier in my life to get me to that point) and the more I study it, the more I see how different it is from any other "sacred" book or writings.
It is both simple (in the sense of being straightforward and not convoluted) and profound.