The biblical argument has two parts. First, there are the clear condemnations of homosexual practice. Second is the clear message that heterosexual marriage is the only proper place for sex. Nothing in the Bible suggests acceptance of homosexual practice as well. It is important to say at the outset that the Bible talks about homosexual practice, not homosexual orientation or "homosexuality," a concept only invented in modern times.
Genesis 19 and Judges 19 – Sodom and Gomorrah and the parallel story about the rape of the Levite – clearly show homosexual rape of guests as a horrible thing. The rape, and the gross mistreatment of guests, are reason enough to condemn the bad people in these stories. But I also think that the fact that a homosexual rape was the outrage that the bad people committed is in the story to show that they were as bad as they could possibly be. This is evidence of the Bible's condemnation of homosexual acts, though not proof-positive that it is condemned in all cases.
Leviticus 18:22 in the King James Version states: "Thou shalt not lie with mankind, as with womankind: it is abomination." Leviticus 20:13 is similar. Some say this is only meant to condemn pagan temple prostitution. A similar reading applies to Deuteronomy 23:17, 1 Kings 14:24, 15:12 & 22:46 and 2 Kings 23:7. I read these as I do the Sodom and Gomorrah story: they are not definitive law for Christians against homosexual sex; on the other hand, they say to me that the Bible writers and readers took it for granted that homosexual practice was disgusting, especially for men.
Some of the purity rules of the Old Testament were set aside in the New. The condemnation of homosexual practice, on the other hand, was renewed in the New Testament. 1Corithians 6:9-10 says that the makokoi and the arsenokoitai are unrighteous. The King James version translates these terms as "effeminate" and "abusers of themselves with mankind." The latter sentiment is repeated in 1 Timothy 1. I don't know what exactly was meant by these terms, and I don't think anyone else can offer a definitive interpretation. The words are too rare, and the possible range of meanings is too wide. Clearly, though, both are bad, and they have something to do with gay acts.
The major text on this subject in the whole Christian Bible is Romans 1:26-27:
"For this cause God gave them up unto vile affections: for even their women did change the natural use into that which is against nature: And likewise also the men, leaving the natural use of the woman, burned in their lust one toward another; men with men working that which is unseemly, and receiving in themselves that recompense of their error which was meet."
I agree with Richard Mouw, the president of Fuller Theological Seminary and a Presbyterian minister, that this is the text that can't really be interpreted away.
The positive side of the Bible's message about sex is that sex within marriage is good, especially for making, with God's help, the great gift of children. This is the vision that is reiterated from Adam and Eve onward.
Some things that the Bible condemns in some places, it seems to allow in others. The passages about women keeping silent in churches had to be weighed against those talking about women prophesying and praying in order to get the total biblical picture. This was why the Presbyterian Church, and many other Protestant denominations, came to accept women's ordination after a long interpretive argument. The same goes for divorce, which I think is the interpretive problem that most resembles the homosexual question. Divorce is condemned all the time, but tolerated under certain conditions. I do not see any parallel texts in the Bible even tolerating homosexual practice.
I therefore follow the teaching of the Presbyterian Church (USA) and nearly every other Christian body on earth: homosexual practice is a sin.
BUT, and this is a very important point, we all commit sins. We are all habitual sinners. Being sinners does not prevent us from being officers of the church, or good citizens, and it is certainly no obstacle to being a church member. That is a point for another blog post.