He was illiterate. He didn't pretend.
Answer me this - if we use the Bible and the life of Jesus (AS) as a template for Christianity, which it's meant to be - how can you reconcile the various pagan rituals which have now become an integral part of Christianity (Xmas, Easter)? To me Christianity is an amalgamation of different pagan beliefs and practices (along with orthodox Christian beliefs) and modern day Christians rationalise them in this context. To me, it seems that a religion that was once true has been corrupted by man, and therefore is no longer valid.
Furthermore, the nature of the Bible is a copy of a copy of a copy of a mistranslation of a copy of a copy of a mistranslation etc which means, the word and meaning has been changed over time and cannot be relied upon. Therefore, in terms of contradictions in a holy book, the Bible is rife with them.
If anything, I'd say the average Muslim follows the teaching of Jesus (AS) closer than the average Christian. The Bible forbids pork, alcohol, but the majority of Christians don't follow these. In fact, I'm sure as part of a Christian ritual there is one that involves the drinking of alcohol.