Here is how I handled a similar situation.

I asked the person if they believe the Bible is the God's word. He responded: "yes I do".
I then asked him to look at a few passages on homosexuality and tell me what they mean.
His response was exactly what the author had in mind.
Over the next few weeks and months, I saw this person repent and it was obvious that this person had been converted.
As far as I know (though I lost touch with him) he is still on the straight and narrow.

In this particular case, all I had to do is point him to the Bible and let the Holy Spirit have His way.
Fortunately, in this case I didn't have to rebuke him because of incorrect use of Scripture.