I think atheism is just like any other religious belief, the people who get noticed and remembered are the offensive and fanatical ones. So we have stereotypes of elitist snobby condescending atheists and wild eyed fanatic christians. Both are only fringe groups that probably don’t well represent the majority of people with similar beliefs.
From my perspective (Atheist) the people that display the most cultural elitism tend to be from the bible belt states. They will simultaneously claim to dislike the northern elitist snobs, but do all the things they accuse others of doing. I think most atheistic elitism is just response to what is already in place. How much more condescending than “you are immoral because you don’t have the FEAR OF GOD in you, also I will never ever vote for you or anybody like you” can you get? Hypocrisy.
Athiesm hasn’t hurt Pete Stark, he seems to be just as popular in his district as ever. Contrary to foreign misconception, the United States isn’t full of Bible Thumping extremists.