Christians and that Damned Non-Christian Old Testament

Okay, so I'm not gonna go completely nuts here, but on Facebook the other day, some blooming nut was talking about homosexuality and claiming that "the Lord" whom he followed as a Christian, had spoken about it, condemning it. Backing up his argument he quoted from Leviticus in the Old Testament. Sort of sent the hair on the back of my head curling and I had to respond. This was my very simple point:
I'm always surprised when people who call themselves Christians drag out the Old Testament, which is not in any way Christian. It ends when Christ was born--assuming that happened and so forth. And Christ, as we are told through the various gospels--stories--written about him over the years, never said anything about homosexuality. He did discuss and condemn greed and hatred, among other things, preached forgiveness, acceptance, and love, among other things, but never discussed homosexuality or said anything about abortion or prostitution or any of the other things that so many people who call themselves Christians appear to condemn. For those perspectives they have to cherry-pick that old testament, which, again, has nothing to do with Christianity or Christ. Just pointing out the obvious, I know.