(CNN) -- The world's oldest known Christian Bible goes online Monday -- but the 1,600-year-old text doesn't match the one you'll find in churches today. Discovered in a monastery in the Sinai desert in Egypt more than 160 years ago, the handwritten Codex Sinaiticus includes two books that are not part of the official New Testament and at least seven books that are not in the Old Testament. The New Testament books are in a different orde...