David Praeger gave the best explanation of that I ever heard: he pointed out that if people aren't religious, they don't believe in nothing; the human spirit needs something bigger than itself to believe in. The largest, most authoritive entity that "atheists" can believe in is government.
Liberals end up putting so much stock in government, it becomes an infallible, all-important "God" to them.
Persons who are religious believe in something greater than governments. Thus, it's easier to for them to step away from government, find it fallible and distrust it.
At first, David's observation seems like hyperbole but the more I've thought about it, the more dead-on it seems to me.
Makes no sense. Many atheists are libertarians, and support a far more limited view of government than social conservatives do.