Bible can mean simoly an important kind of book in English. Although when we say the Bible meaning the Christian scriptures it should be capitized, we would not if we say the Camel Book is kind of a bible of Perl. Christian is an adjective so not capitized. Christianity should be as a specific proper name. Koran and Islam are specific names. Now Islam and the Koran are horrible...but that doesn’t matter for capitalization. We even capitilize Hitler and Stalin because they are proper names. Even Hilary Clinton is capitilized!
Oh The huge manatees !
That may be true but we all know what we mean when we use the Bible in context.