I always hear Christians saying people who are gay aren't Christians, but a Christian can have premaritial sex and still be a Christian just may be living in sin. How does that work? Any opinions?
Gays have become a popular Other. We are clearly on the other side of the fence, so if you are not standing with us it follows that you're on the correct side. Granted, we're not as visible as black people, Jewish folks, Nazis, or other groups which have been used to reinforce group identity, but we're visible enough, especially recently.
By focusing on someone so clearly lost as the homosexual, the pious church lady's gossip, the teenager's premarital sex, the deacon's tendency to casual wrath - honestly, who cares? If you blur the line in the sand and begin to consider
heterosexual sexual immorality, you might have to consider all sorts of other sins; the line loses its utility. The game is no longer fun to play and a holy God's eye passes back to the person for whom not being homosexual is no longer sufficient protection.
Of course, when called on things like heterosexual immorality or lying, the average Christian will focus on it for long enough to pass the necessary judgment. Time will pass, however, and their attention will move back to the game.