and in the debates that endure between different people of different beliefs, as to how right or wrong it is, there will be no winners, since either side will hardly ever accept the reasoning or proofs of the other.
Personally as a Muslimah I know homosexuality is accepted to be a sin according to the Quran and sunnah(of course not a evidence accepted by all non Muslims), a major sin yes, but then so is sex out of wedlock. So is backbiting and slandering. So is being un-dutiful and cruel to one's parents(in fact this is a sin often mentioned to be a far bigger sin than others).
If I know a Muslimah or a Muslim to be gay(and I have known) Then I would advice them from the Quran and Sunnah as to why it's better for them to abandon their deeds. If they accept it well and good. If not then Allah will judge them. They are still Muslims, just Muslims committing sins.And since non of us are pure of sins,I will just keep advising them in the best possible manners. We are all tested with our desires after all, sexual and otherwise. Sometimes we overcome them and sometimes we don't.
I know personally one gay lady who was a non Muslim and became Muslim. She accepts being gay to be a sinful and works hard at controlling her desires. It's not always easy but she does so to please God. And I admire her for that.