How many atheists believe in God?

The Pew Forum on Religion & Public Life today published the second half of a massive study on American spirituality. (The first, which found Americans change faiths frequently, appeared in February.) The new portion is full of information; some, like the fact that religion is “closely linked to political ideology” and that many Americans consider themselves spiritual but not dogmatic or even belonging to a specific religion, is not that surprising. Neither really is that 42 percent of Americans consider the entertainment industry a corrupting cultural influence.

But what about the 21 percent of Americans who say they don’t believe in God but aren’t sure of his non-existence?