Comment 1 by Sjoerd Westenborg

...why are atheists so distrusted in the US?

Tom Rees at Epiphenom discussed this with the help of some research. Atheist dislike seems to be due to a lack of trust, brought on by a sense of their 'otherness'. In societies where atheists are more common than in the US, atheists are less disliked. I suppose the thinking is that in a theistic society like the States (despite the constitution) not many people know an atheist, so fear their 'difference', but atheists don't have a similar distrust of theists (on the whole!) because they know plenty of theists whom they trust.

Remember that John Locke, famous for preaching tolerance for other faiths, drew the line at atheists:

Promises, covenants, and oaths, which are the bonds of human society, can have no hold upon an atheist. The taking away of God, though but even in thought, dissolves all.

Thanks for that, Lockey!