What does the average US conservative think of atheists?

You'd gain more traction trolling leftists by saying politically incorrect things. But to answer your question, it depends on whether the atheists are intolerant militant morons who want religion stamped out or are simply people who hold an atheist belief without hating religion. Conservatives generally think Ayn Rand was cool, because she was pro freedom, and there are atheists around with more positive views of religion's impact than she had.

Many conservatives could actually care less about atheists; the only god that matters to them is the almighty Dollar (and its siblings: gold, silver, property, stocks and bonds, etc). Many of them give hypocritical lip service to religion (like most Republican politicians), but their real saviour is money.

Religious conservatives, on the other hand, DO hate atheists, or perhaps a better description would be that they don't give a crap about what they think because they consider them outsiders who aren't "saved" and therefore they aren't worth caring about. Loonies like Fundamentalis and Evangelical Christians fit the bill here, and there's plenty of smaller fringe denominations that are even more whacko.