The scriptures don’t necessarily condemn gay marriage. The Bible includes many outrageous statements: Paul says women shouldn’t speak in public. YHWH asks for people to kill one another. Et cetera. I can provide specific references upon request. CF
dignityusa.org’s FAQs:
Q: What part does the Bible play in deciding the morality of same-sex acts?
Unlike some other Christian churches, the Catholic Church does not rest its teaching on the Bible alone. But the Catholic Church does appeal to the Bible to support its teaching about natural law. Church documents claim that, from Genesis to Revelation, the Bible consistently opposes homogenital acts.
However, contemporary Bible scholars raise many questions about the matter. Read within their own historical and cultural contexts, the Bible texts do not address adult, loving homosexual relations as we understand them today.
Q: What was the point of the Bible texts if not to condemn homosexuality?
It is not easy to summarize the body of research on homosexuality in the Bible, but these are the interpretations that some scholars are proposing:
The story of Sodom in Genesis 19 is about offense against the sacred duty of hospitality. That is how Ezekiel 16:48-49, Wisdom 9:13-14, and Ecclesiasticus 16:8 unequivocally interpret this text. The attempted male rape only heightens the atrocity of this offense against charity, the paradigmatic biblical sin.
Leviticus 18:22 does forbid male-male sex as an “abomina tion.” But the word simply means an impurity or a religious taboo—like eating pork—and it only applies to penetrative anal sex, not other male or female same-sex acts. Such religious requirements were to maintain and strengthen Jewish identity. As in the case of Catholics who used to be forbidden under pain of mortal sin to eat meat on Friday, the offense was not in the act itself but in the betrayal of one’s religion.
Romans 1:27 mentions men having sex with men. But the terms used to describe it are “dishonorable” and “shameless.” These refer deliberately to social disapproval, not to ethical condemnation. Moreover, according to Paul’s popular usage, different from the technical Stoic philosophy of the day, para physin (“unnatural”) should be translated “atypical” or “beyond the ordinary.” It bears no reference to natural law. And it can imply no ethical condemnation because in 11:24 God is said to act para physin. Paul sees gay sex as an impurity (1:24), just like uncircumcision or eating forbidden foods. He mentions it to make a main point of his letter, that the purity requirements of the Jewish Law are not relevant in Christ Jesus (14:14). See L. William Countryman, Dirt, Greed, and Sex.
1 Corinthians 6:9-10 and 1 Timothy 1:8-10 list arsenokoitai among those who will be excluded from the Reign of God. This obscure term has been translated “homosexuals,” but its exact meaning is unknown. It certainly does not include women but refers to some kind of male sexual offense, probably involving money. If it does mean men having sex with men—which is dubious—it presumes the abuse and licentiousness commonly associated with male-male sex in the Roman Empire. See Robin Scroggs, The New Testament and Homosexuality.
Finally, Genesis 1-3 shows Adam and Eve created for mutual companionship and procreation. These accounts use the most standard of human relationships to teach a religious lesson. The point is the love and wisdom of God, who made all things good and wills us no evil. Nothing suggests the biblical authors intended a lesson on sexual orientation.
Hope this clears up the Scripture question for you!