and decided not to anymore.

you're operating off the assumption that KNOWING about God, his existence, and nature, perhaps even consulting and dealing with him personally...that one will continue to.

belief as you know is nothing without a manifestation of it. beleif alone is nothing...it doesn't DO anything. as such, one can KNOW something during a belief state and then stop believing it, but KNOW and REMEMBER everything from that time. how you deal and operate off that belief is what others see. the devil KNOWS and BELIEVES in God, even knows the outcome of his predicte attack upon heaven...but operates in opposition to it! :)

that's ONE answer...

another one is by having a seriously advanced ability at multitasking. one that allows the understanding of unreconcilable concepts (i.e. understanding but not faith/or adherance) to particular ideologies.