I think the RC explanation of the relationship between orientation and act captures the point well by referring to homosexual attraction as "objectively disordered desire." In other words, the act is always wrong because the desire to perform the act is, unlike normal human functions like eating and "mating", only a result of the fall. It is therefore, unlike eating done by sinners, or sleeping, or marrying, or most common actions performed by sinners, not redeemable. Those who do it are redeemable, of course, by repentance and faith, but the act itself is not something that can be "baptized" and made holy again, like eating and marrying, because the act itself is a sign of the fall. Nobody is saying the desire isn't sincere. The question of whether people were born that way is moot. Nobody is saying it is simple not to engage in something your whole being cries out to do. Nobody is saying homosexuals per se are worse than other people or that their sin is worse. They're saying that sodomy, as an act, is not redeemable, whereas heterosuexual sex between married people is redeemable. It is like idol worship. Idol worshippers are redeemable, but idol worship is not; it, like sodomy, has no legitimate place in the Christian life.
