My advice to atheists is to engage Christians on their sense of justice and of empathy. I give that advice in the hope that Christians themselves would work out how to accommodate gay relationships.

I don't want to get into close Bible study on this because Christians do not accept such studies coming from atheists: many of them have the idea that non-Christians cannot interpret the Bible correctly, and this idea provides a theory of justified dismissal for any interpretation from an atheist which they don't like (you can see that on the uk.r.c thread: Mark Goodge wasn't interested in engaging my interpretations specifically because I'm an atheist and so don't have to abide by what the Bible says).

So, it's much better if Christians themselves come to an accommodation, even tacitly, as many of them have on divorce. No doubt if they did reach such an accommodation, it would have been written into the universe's blueprint all along: after all, there are no lies in religion, as Ken Macleod tells us.