BOSTON — Atheists are under attack these days for being too militant, for not just disbelieving in religious faith but for trying to eradicate it. And who's leveling these accusations? Other atheists, it turns out.

Among the millions of Americans who don't believe God exists, there's a split between people such as Greg Epstein, who holds the partially endowed post of humanist chaplain at Harvard University, and so-called "New Atheists."

Epstein and other humanists feel their movement is on verge of explosive growth, but are concerned it will be dragged down by what they see as the militancy of New Atheism.