Although there already exists a meaning for this, i would like to make it a neologism related to Athiest vs Agnostic. The root of the word, from the Greek apatheia, meaning without feeling, is not an exact meaning, but i think it sounds a lot better than "Indifferencism" or "Indifferencistic" (try saying that three times fast).

Basically, the main concept is that one is indifferent if there is a god or not, does not bother to spend time thinking about the existence or non-existence of a deity, and does not care what a god (if one existed) would do to him or her based on his or her actions.

Of course, this could all be attributed to laziness, but personally, I think there are more important things to worry about and bigger problems to solve.