I wouldn't either
"I personally would never vote for someone who considers himself an atheist."
You're not every likely to face that situation. Few atheists believe that they could successfully run for any office while professing their atheism.
That is not to say that atheists have not won elective office, but they did do without saying that they were atheists.
Remember, just because you see someone coming out of a church, you cannot be sure of that person's beliefs. You might even see me coming out of a church. I visit churches of different denominations on a pretty regular basis. These days, I go to a Russian Orthodox church about once a month. I enjoy the liturgy and music there.
The funniest thing about this entire question is the definition of who is a Christian. In my time on Free Republic, I've seen declarations of the non-Christianity of a number of denominations fo Christianity.
What appears to be the common ground in these declarations that a particular denomination isn't really Christian is that it disagrees with the particular dogma of the poster.
Indeed, the most common target of these claims is the largest denomination of Christianity. If I've seen one post claiming that the Roman Catholic Church isn't really a Christian church, I've seen a hundred.
Go...believe as you choose.