I am a Buddhist and an atheist. As for the subjects of reincarnation and other afterlife stuff, I am indifferent. I just know that chanting Gongyo and Daimoku make me feel deep inner peace and since I am only interested in what is tangible, I practice chanting to feel inner peace. Maybe in the same way that some atheists don't really believe in a god, but pray sometimes just because it makes them feel better.