Just one actually - and I am sure that if my college knew, they'd disassociate themselves
Being a liberal, agnostic, swinger friend of the gay and lesbian community - I have sort of lost my perspective. My answer now would be - "who cares?" I mean, really. If Jesus was the Son of the Old Testament God (and the two were in fact one), then everything that the Old Testament God did was done through and agreed with by Jesus...
You can't really separate the two.
But - as far as your answer goes - you already have it in your definition of adultery. Jesus said that the two greatest commandments - and the two on which the entire law hangs - is to love God with all your heart and mind and to love others as yourself. That's it.
Not "be faithful, clean-mouthed, well-dressed, in church every Sunday, right about everything, a non-smoker, a listener to Kirk Franklin, chaste, a watcher of only "G" rated movies (except those made by Disney since they support queers), etc." The church has made too many damn rules...
Jesus didn't.
Sure - he took issue with a few things - mostly self-righteousness - but he never, ever said swinging was wrong. Yes - he was against lust and adultery - which in context was a form of thievery. He was not against love, happiness, laughter - and all the good things that life has to offer.
Jesus was saying the Matthew 5, a portion of the Sermon on the Mount, that if a person looks at a woman to lust after her, he needs to pluck his eye out and throw if from him. He was pretty extreme with his prescriptions here - and if we want to take him literally, then there would be a lot of blind men walking around - your friend included.
He also prescribed cutting out the tongue and cutting off hands...
Strong language...
But yet - his disciples were not self-mutilated...
Nor has any mainstream religious group taken his teaching literally. Sure - literally enough to tie people up with guilt, but not nearly enough to start lopping off parts.
Complete piety would be, quite literally, lame!
Actually - if we take the Sermon on the mount and filter it through the "greatest commandments" we have some awesome advice for swinging couples! What sort of place would the lifestyle be if people respected one another? If men looked at women as art - as treasures - as friends; and women returned respect for respect.
Friendships would be more common, jealousies would be far less, hurt feelings and bed notchers would be rare.
Was he saying don't look at a woman as a sexual being? What sort of crazy, fucked up god makes men visual and then punishes them for looking? It is insane that anyone would think that this makes sense. No - Jesus was telling us to look at each other with respect. To not turn women into objects to be possessed, lessened.
Sex is a part of our nature - the sliminess we learn
Now - will this argument convince your J-Dub friend? I am sure that it will not. However, swinger or not, it is the position that makes the most sense given the over all context of the Biblical story.
In my opinion, anyway
PS - To be fair to myself, I wrote this right before bed and I am pretty tired. So the "outline" is sloppy. If it makes no sense - let me know and I'll explain my points better.