I’ve heard this discussed, that atheists have a high negative rating; that a large number of voters would not vote for an avowed atheist for public office. Whereas prejudice against minority, homosexual, divorced, women candidates for office has greatly declined in recent years, prejudice against generic atheist candidates for office is still strong. According to some polls I have seen.
The reason is that we don’t really know what they believe in. Even in my atheist days, I had more confidence dealing with Christians & Jews because I knew where they stood.