How about this: Extreme atheism is a faith; uncommitted atheism is a philosophy, but not a faith.
So it seems, but I really don't know enough about the extreme atheist's position to flat-out say that it's held on faith. It may be just faulty reasoning. In any event, it's certainly not a religion. At least not what I would consider a religion. (Not unless it's coupled with other things, like rituals, scriptures, dogma, etc., which I've never heard of.)