When a politician or celebrity uses quotes from the Bible to gain credibility and/or publicity. The word comes from a combination of the Bible and from a bastardization of "poetry slam." A poetry slam is a competition where "poets" drop random prose or bullshit in the guise of artistry to impress laymen and seem sophisticated. Politicians and celebrites are especially prone to the tendency to bullshit and therefore quote the Bible.
Joe: Dude did you see the presidential debatelast night?!
Joey: Nope.
Joe: Aw, then you missed Mitt Romney bibleslam the shit out of Obama!
Joey. Now I am really upset that I missed that debate. Wait...What?
Biblesplaining: making excuses for things that don't makes sense in the Bible, or validating The Bible by adding one's own personal explanations- for the purpose of denying one's own doubt, or to persuadesomeone else to believe the fantasy.