Statically, atheist are only more hated then scientologist. [1] And like I can't think of a clear reason that a level headed society would feel that way. Atheist don't do anything wrong as a whole (and most other religions have at some point or another), and I don't have the website, but 10% of the population are atheist, but about 1% of the prison population are altheas [2]. So; Statistically, when measured an atheist is 10 times less likely to be in jail then a religion, when scaled to account there are less atheist then people who believe in something.
Infact; a handful a states, even northern ones like Penslinvaina have clauses in there construction that prevent atheist form holding public office, and more bluntly Arkansas [3]
What do you think new grounds?
1: http://www.gallup.com/poll/106516/americ ans-netpositive-view-us-catholics.aspx
2: http://www.skepticfiles.org/american/pri son.htm
3: "Atheists disqualified from holding office or testifying as witness" (section one, Arkansas constitution)