Actually there are many Buddhist Christians ... including many priests and ministers. Buddhism doesn't affirm the existence or nonexistence of deities. Some Buddhist sects incorporate deities that were worshipped in their respective cultures before Buddhism; others don't. Your mom might be interested in this piece about Buddhist Catholics. http://ncronline.org/news/double-bel...hristian-faith

(Also, Muslims believe that Muhammad was a prophet, not a deity ... Muslims worship the same Father God that Christians and Jews do, that's why all three are considered Abrahamic religions ...)

I would think that the percentage of practicing Christians who don't actually believe in God is actually a bit higher than that 5%. But if 5% will admit to not believing in God at all, then it stands to reason that some other proportion would have a concept of god that's at odds with Christian orthodoxy, right?