Try having this discussion with an actual homosexual person sometime. It is not fun. I have one in my family who claims to be a Catholic. I explained to him why he cannot be a true Catholic when he is a sinner in the eyes of the Church. He did not want to hear it. I will send him this article though. I believe he can be saved.
Try having this conversation about contraception, sterilization, premarital sex, divorce and remarriage ... same story. When people feel that their sins are essential to their lives, they're very upset about the plain word "sin," never mind all the physical or psychological health discussion.
If the point had carried with heterosexuals over the last 40 years, I don't think we'd be having the current issues with homosexuality at all. There just aren't that many homosexuals; the resistance to traditional morality has the force of the majority behind it.