Answer
Salam (Peace) Dear Simone,
Thank you for your question and I really appreciate your sincere feelings towards your friend.
My opinion is that our love for our dear people should be a way to rescue them when they are in danger. Sometimes true friendship implies that we should behave firmly with whoever is hurting themselves and endangering society, when they are too weak change.
Your friend’s situation is very critical, not only from the religious point of view, but also regarding his mental, physical and psychological health.
As for the religious aspect, Islam is not the only religion, which condemns such relationships. Since the dawn of history, people were warned against it, through the repeated telling of the story of Lut’s people, the way God condemned them and the tragic end they met for having such sexual orientation.
You can read this story in the Old Testament in the Genesis (chapter 19) and in many parts of Quran as well. For example
The people of Lut rejected the apostles.
Behold, their brother Lut said to them: “Will ye not fear (God)?
“I am to you an apostle worthy of all trust.
“So fear God and obey me.
“No reward do I ask of you for it: my reward is only from the lord of the Worlds.
“Of all the creatures in the world, will ye approach males,
“And leave those whom God has created for you to be your mates? Nay, ye are a people transgressing (all limits)!”
They said: “If thou desist not, O Lut! thou wilt assuredly be cast out!”
He said: “I do detest your doings.”
“O my Lord! deliver me and my family from such things as they do!”
So We delivered him and his family,- all
Except an old woman who lingered behind.
But the rest We destroyed utterly.Surah 26 Verses 160 – 172
We also (sent) Lut: He said to his people: “Do ye commit lewdness such as no people in creation (ever) committed before you?
“For ye practise your lusts on men in preference to women : ye are indeed a people transgressing beyond bounds.”
And his people gave no answer but this: they said, “Drive them out of your city: these are indeed men who want to be clean and pure!”Surah 7 Verses 80 – 82
These, along with about 25 more verses, in which this story was mentioned in less details show the magnitude of this sinful conduct and the amount of abhorrence God has for both gays and lesbians, even if it is the only sin they commit in their lives.
On the other hand, your friend should be aware of the major health problems, in both the short and the long runs, which homosexuals are exposed to (e.g. HIV/ AIDS).
What I am trying to tell you here is that your love for your friend does not mean that you have to accept him as he is! Rather, your love should be interpreted in standing by his side, as much as you can. This, while you are aiming to help him so that he can finally give up such a habit, which will destroy both his life here and in the hereafter!
I do understand that old habits die-hard and that it may give you a hard time to go through it till the very end. But, that is what friends are for!
Good luck and we hope to hear from you again.
Salam.