Some thoughts in response to the argument that homosexuality is bad if it results from nurture but may be all right if rooted in nature:
I'm not sure the nature/nurture distinction is really quite so distinct. Postmodern theorists would argue that all of reality is socially constructed, including sexual identity. While this seems to lead to a nurture viewpoint, it really is an ontological claim about all of reality. Our nature is that we are socially constructed. There is no tabula raza that constitutes our identity prior to whatever social, "nurturing," forces exert themselves upon it.
Now, I'm not entirely a postmodernist, but I don't need to be to escape the nature/nurture distinction. I just have to say that human sexuality is more complex than the binary between homosexual and heterosexual. Queer theology looks at Gay, Lesbian, Bisexual, Transgender and other queer identities. It's not even a linear spectrum; it's more like a color wheel, or better yet a sphere, with some people locating themselves in varying relations to all of the different factors. Research suggests that most "heterosexual" people have homoerotic thoughts at various points in their lives about people of the same sex. Similarly, "homosexual" people have heteroerotic thoughts about people of the opposite sex.
So, what then are we to make of this theologically? I would say that for most people, their human nature is to have some sort of place in the sexual identity sphere that is a mean value but that throughout their lives they will move around a bit within the sphere. This is how God created us and it is indeed good. This is our nature. Our nurture, our social construction, on the other hand, functions to sector off certain sectors of the sexual identity sphere as bad. Evolutionary psychologists such as Jonathan Haidt see this practice as part of human adaptive sensibilities to survive in a sometimes hostile world. Theologically, I would say that the human fall, sectoring off parts of the sexual identity sphere, is a result of and deeply interconnected with the fall of creation that makes creation sometimes hostile to human thriving. Salvation really is with Christ who reestablishes the full sexual identity sphere and overcomes the hostility between creation and human thriving, at least potentially. We are sinful, therefore, insofar as we continue to reject the careful balance inherent to the created world and reestablished by Christ and therefore also continue to reject the fullness of the sexual identity sphere.
This is not a judgment. It is a theological position. I've found it helpful. Perhaps others will too.