What is the fundamental principle of the New Testament? It is one of universal love. Loving your fellow man. And if we get obsessed with a particular definition of that through a form of sexuality, then I think we are missing the centrality of what the gospel - whether you call it a social gospel, a personal gospel, or a spiritual gospel - is all about. And therefore, if you think homosexuality is an unnatural condition, then frankly, I cannot agree with you based on any element of the science.
I wish I could feel bad for that man's crestfallen face when Prime Minister Rudd brings up that whole slavery bit of The Bible. Sorry bro.