"Why are the "neo-atheists" of today so obsessed with God's nonexistence that they go on media rampages, wear T-shirts proclaiming their absence of belief, or call for a militant atheism?"

Are they? The whole premise of the article rests on whether or not you actually believe that to be true. Personally I don't, so, to quote Sillitoe's Arthur Seaton, "….all the rest is propaganda".