I'm reading a book called Buddhism without Beliefs right now. Atheism comes out of an attachment to an ego that thinks it has the answers. Gautama himself was a humanist, he simply didn't care and wouldn't respond to questions about metaphysical origins of humanity or the afterlife. He was all about freedom and inner contentment in this lifetime.

You don't have to give up your own religion to pick up buddhist philosophy, either. You meditate in the morning and pray at night.