Without citing the bible, what marks the bible as the one book with God's message?

[Ahriman]

Sure, and in old magic book before it we're pretty certain that "moses" didn't narrate his own death.  Either way, assertions are made.  The belief finds it's literary expression.

That said, the belief expressed then isn't exactly concordant with contemporary christian belief - where much of the asserted exclusivity and divine provenance of magic book and what it says has given way to massive purchase in new age beliefs and contemporary societal mores held alongside or even over traditional christian beliefs and mores, by self professed christians.

Modern Christianity doesn't mean a whole lot. Religious fanatics are the only ones who have got it "right", so to speak.