The unstated assumption in my OP is that each are publicly known. No one is hiding their homosexuality or atheism.
Maybe you just have more trust in politicos than I do. When I hear one talk I assume that they are lying about something, if only by omission.
That said, I wouldn't have a problem voting for an atheist on principle. I am one, no prob. I might question their judgement. Why tell people irrelevant stuff that hurts your electability? Can't you lie for a good reason? Politicians need to know when to do that.
I'd have more issues with a gay candidate. I know a lot of gay people and most have suffered psychological damage from growing up in a homophobic society. At the local level it wouldn't be a big deal because people know them. Even at the state level they're more accountable. At the federal level its a different story. The billionaires and the spin doctors and the election consultants can make anybody electable. Sarah Palin was on a presidential ticket for God's sake. I'd need to know a lot about a homosexual for President before it stopped being a minus point on my personal check list of needed info.
Down the road a decade or two my issues with gay people might cease to be important. I certainly hope so. But for the foreseeable future ...
Back when Obama was running against McCain, a gay woman was running for city council here. I knew her very well and I didn't much like her PC extremism. But, OMG, I could vote for a black guy and a dyke here in rural southern Indiana! I knew it didn't matter who I voted for, neither were going to win here. But I didn't care, it felt really good!
Tom