You mean wrong from a religious perspective?
I had friends who were gay. I wasn't particularly religious at the time. They all died young of aids. Young men tend to be particularly promiscuous. One gay friend said he had sodomy with over a thousand different men.
Even if AIDS doesn't get you, there are all kinds of health problems with sodomy: antibiotic resistant STDs, kidney infections, anal prolapse, anal tearing... whole long list of diseases and complications.
If I was to try (and like I said, all the gay people I knew died, mostly of aids and complications of aids) I'd point out how dangerous it is, explain that being same sex attracted is a cross we must bear and point to the scripture on how we all get a cross, point to the old testament quotes on Sodomy and the Punishment and explain that was to prevent the spread of STDs that killed entire families and that it was really out of God's love for those who would otherwise restrain themselves.
And just being homosexual isn't the problem. That's the temptation, the cross. Just like being heterosexual can be a cross if it's inordinately strong.