Don't want to skip over Mickiel's interesting question, but here are some other thoughts on the subject;
Romans 1:26-27: "For this reason God gave them up to vile passions. For even their women exchanged the natural use for what is against nature. Likewise also the men, leaving the natural use of the woman, burned in their lust for one another...this passage to this point is not talking about "specific, debatable behaviors"...it is talking about lust, desire, for the same sex...and that being against nature (or God's creation)
1 Corinthians 6:9-10: "Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor *homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God."
*In this passage Paul coined this specific word for homosexuality. It is made up of two Greek words: "arsane," meaning male, and "koite," meaning couch or bed. Many of the terms at that time described not so much homosexual people but homosexual acts or behaviors. If Paul had used any of those terms, those would have been limiting terms. ... In this instance he was going for a broad condemnation of any erotic male-male contact. (per Joe Dallas, ex-gay member of Metropolitan Community Church and former homosexual activist, now provides scripturally-based lectures on homosexuality)
In Matthew 19:5-9 Jesus defines marriage as being between one man and one woman...man, woman, cleave together, one flesh...
IMO, anything else is just a stretch.