Why is gay sex biblically condemned? Not your usual answer ...

I was wondering what I was going to read when Matt Stone drew attention to this article by  Nigel Chapman
Gay Sex for Evangelicals - Chapman-2013_Gay-Sex-For-Evangelicals_v1-4_26-April_final.pdf: I thought it might be a simple restatement of what is currently the usual evangelical stuff on the issue, but as it was Matt, I wondered. Have a look, but if you want a sense of why,

 To answer my starting question: Why is gay sex biblically condemned? Because it is profoundly abhorrent and immoral in the cases which scripture addresses, and for the reasons which it gives. But as Romans 1 makes clear, the case we must address is different. When the reasons that establish immorality and abhorrence in the biblical cases are applied to permanent and involuntary same-sex attraction (orientation) and faithful and monogamous same-sex unions (gay
marriage), then we see a clear and clarifying pattern: the reasons that condemn do not apply, and
the reasons that apply do not condemn. Biblically, this case is not the good but unattainable ideal. But just as biblically, it’s not a moral evil. We should stop treating it like one

  It doesn't deal with the argument drawn from Genesis 1 and 2 but others have done that. See here. Also commend this book for a closer examination of the other exegetical issues.