Since this is a Roman Catholic forum let’s go with Roman Catholic teaching.
The Church’s teaching on homosexuality is based on Truth. This is expressed in the words of the bishop, St. Cyril of Jerusalem: “The Church is called Catholic or universal because . . . it teaches fully and unfailingly all the doctrines which ought to be brought to men’s knowledge, whether concerned with visible or invisible things, with the realities of heaven or the things of earth.” In other words, the conclusion that homosexuality is disordered is based on the Truth, not just on Catholic teaching. Yet, saying that makes this conclusion all the more controversial.
If it were based simply on Catholic teaching, opponents could say: “You Catholics are entitled to your opinion, but that is not binding on others.” Instead, saying that Truth is the reason that homosexuality is disordered… is offensive to those who deny the existence of Truth, who prefer to live in a world dominated by what Pope Benedict XVI termed a “dictatorship of relativism.”
If you acknowledge that Truth exists, then we can discuss and even argue about whether or not I or the Catholic Church correctly understands the Truth of this matter. But if you deny that there is such a thing as Truth, that is, the Truth, not just my truth and your truth, then the matter becomes merely an exercise of raw political power in terms of who has more votes to impose an agenda, and that is what makes it ultimately tyrannical.
Functioning according to nature or design. Not defined by popular opinion.