It is being widely reported that Steve Chalke has "come out" in favour of gay marriage. Here's his paper on it, and here are some more resources on it. Peter Ould, whose thinking I generally find very helpful on issues around homosexuality has started a reply here, which show that Chalke's work on the Bible passages is somewhat lacking.
I agree that at times the church has been guilty of hatred of people who experience same-sex attraction, and that we need to repent of that. However, I don't think we should change the Biblical understanding of marriage in order to do that - that would seem to be something of an extreme over-reaction.
I'd want to add three more questions for Steve Chalke:
1. Why do you put people into boxes marked "homosexual" or "heterosexual"? Isn't that part of the problem?
2. Is there any evidence in the Bible either that sex outside marriage should be permitted or that marriage should not always be between a man and a woman?
3. Do unhappily single people have the gift of celibacy?