Wow this thread is LONG! I've been too busy at work to add anything more than trivial one-liners on Mumsnet, so have read through all of this with much interest, thanks everyone. I'm afraid I can't remember who has said what exactly, so I'm just going to add my own thoughts generally (which I'm sure won't make sense, ds is screaming blue murder at the mo).
I will also put my head on the block and agree with Bloss and others that homosexuality is wrong, and so is sex before marriage (and yes, I had a major struggle with the second point!) God is not anti-sex - he created it in the first place for our enjoyment as well as procreation, but within certain boundaries. The AIDS aspect has been mentioned, which is relevant to some extent today, but I think the main reason is that God sees the actual sexual act itself as binding, rather than a piece of paper at a man-made religious ceremony. Adam and Eve didn't walk down the aisle and say 'I do', they became 'one flesh' through sexual union. It seems that people are trying to find 'loopholes' in God's word about sex before marriage, when there is no need to look for a verse that says premarital sex is a sin, the Bible is already clear that all sexual immorality is sin.
In a similar manner, many Gays try to justify their homosexuality by stating that Jesus never spoke out about gay sex - he also didn't mention incest or rape, but we know they are wrong, we don't need to be told.
I am certainly not anti-Gay, and no sin is any worse than another, but the Bible is very clear on these subjects.
Must go now and deal with ear-piercing screams from ds!