This is Atheism.
There is no “Apathy” to a claim of knowledge. You either agree with the claim or you do not agree with the claim. “God exists!.” If you believe the claim you are a theist. If you do not believe the claim you are an atheist. Apathy has nothing to do with anything. Be as apathetic as you like, when the street preacher gets in your face do you believe him or not?
Most believers are not going to be apathetic towards that belief. The case I can think of; 'I’m going to hell anyway so what the fuck does it matter?"
There are loads of non-theistic religions… so what? They don’t have anything to do with Apathy. They don’t believe in god or Gods and that makes them atheistic.