[I hope this isn't a duplicate. I thought I had posted it, but it didn't how up.]
I'd like to look at Rom 1 again. I've seen, here and elsewhere, a claim that Paul was only speaking of heterosexuals.
First, the passage isn't about homosexuality. It's about idolatry. Hence Paul doesn't speak very explicitly about homosexuality. He just takes it for granted that we see something negative about it. That's one thing that leaves the passage open for multiple interpretations.
Second, it looks to me like he's speaking of the culture as a whole. Because they don't believe in God, pagans are subject to all kind of sinful and abusive behavior. This is one of them (but the one he seems most upset about). From the point of view of pure logic, he could say what he did even if he thought there were a few people who are naturally homosexual.
But since he isn't talking specifically about homosexuality, we have to read between the lines. And when you move from an unnaturally legalistic reading to seeing what the passage says about his assumptions, his statement sure doesn't sound to me someone who thinks homosexuality is OK as long as it involves people who are naturally homosexual. To the contrary, I believe he takes it for granted that natural relations are heterosexual and anything else is contrary to God's design.
For me the real problem is that we're trying to push Paul to speak on issues he didn't speak about. He isn't speaking about homosexuality. He's speaking about paganism. But he does refer to it as an obvious evil. In principle, we don't know what he would say if confronted with Christians who are living an otherwise ordinary Christian life, but with gay sex. It's a situation I'd say he had never thought about.
When the evidence is unclear, it becomes more important than usual to approach the issue objectively, with good judgement. I think the usual interpretation is compromised by the obvious bias of most of the people making it. I would be more sympathetic to someone who says "while Paul isn't speaking directly about homosexuality, his comments are sufficiently negative that we have to assume he thinks it's wrong." However when people treat it as a sin much more serious than ones that are mentioned much more clearly, and deny that there's any ambiguity, I think it's clear that we have influences at work other than sola Scriptura. Now good arguments are accepted even from people who are wrongly motivated. But when it comes down to a matter of judgement, it becomes more relevant whether someone shows signs of good judgement.
Aside from irrational components, it is clear that differences in Scriptural interpretation are a key here. If you think God guarantees every word, with no room for the authors to be writing from the perspective of their culture, you'll follow any verbal hint of an answer. In that case, it's natural that you would say that the Bible condemns homosexuality. If you are willing to make allowance for the cultural context of the discussion, you'll be more open. Of course everyone takes the second point of view on a lot of issues, which is why I find the so-called literal interpretation so hard to take. (Few people get as hot under the collar about women with short hair 1 Cor 11:12 as gays.)
I've seen some comments that I'm not clear on my stand. Sorry, I'm trying to look at Paul's position, taking full account of grays. I understand that on this issue people tend to look only at whether someone agrees or disagrees with them, regardless of what they are saying. I don't consider that a good sign. But to be clear: I think one's conclusion about Rom 1 will be controlled by one's Scriptural interpretation. If one believes in context-free interpretation, one will come away saying the God condemns homosexuality. If one doesn't, one will come away seeing room for the Church to make its own judgement. I believe in the long run that this judgement will be based on whether or not gay Christians live lives that are otherwise similar to heterosexual Christians. If it turns out that -- unless you reject the possibility from the outset -- many gays have relationships that show the grace of Christ in the same way that heterosexual couples do, then I think the Church will come to accept it. If it turns out that there are problems with gay relationships such that they are never truly equivalent to heterosexual ones, then I think in the end acceptance of homosexual sex will remain limited to a few Christians. I can't be any clearer than this without violating the rules of CF.