If everything has a first cause, then God does, too, and there is no first cause. . . . If someone asserts that God is the uncaused first cause . . . we should thus inquire, "Why cannot the physical world itself be taken to be the uncaused first cause? After all, the venerable principle of Occam's razor advises us to 'shave off' unnecessary assumptions, and taking the world itself as the uncaused first cause has the great virtue of not introducing the unnecessary hypothesis of God."
John Allen Paulos, Irreligion