From Politics Daily, citing part of the 130+ page decision which overturned California's Proposition 8 as unconstitutional:
1. "Individuals do not generally choose their sexual orientation. No credible evidence supports a finding that an individual may, through conscious decision, therapeutic intervention or any other method, change his or her sexual orientation."
2. "California has no interest in asking gays and lesbians to change their sexual orientation or in reducing the number of gays and lesbians in California."
3. "Same-sex couples are identical to opposite-sex couples in the characteristics relevant to the ability to form successful marital unions. Like opposite-sex couples, same-sex couples have happy, satisfying relationships and form deep emotional bonds and strong commitments to their partners."
4. "Marrying a person of the opposite sex is an unrealistic option for gay and lesbian individuals."
5. "The availability of domestic partnership does not provide gays and lesbians with a status equivalent to marriage because the cultural meaning of marriage and its associated benefits are intentionally withheld from same-sex couples in domestic partnerships."
6. "Permitting same-sex couples to marry will not affect the number of opposite-sex couples who marry, divorce, cohabit, have children outside of marriage or otherwise affect the stability of opposite-sex marriages."
7. "Proposition 8 places the force of law behind stigmas against gays and lesbians, including: gays and lesbians do not have intimate relationships similar to heterosexual couples; gays and lesbians are not as good as heterosexuals; and gay and lesbian relationships do not deserve the full recognition of society."
8. "Proposition 8 increases costs and decreases wealth for same sex couples because of increased tax burdens, decreased availability of health insurance and higher transactions costs to secure rights and obligations typically associated with marriage."
9. "Proposition 8 singles out gays and lesbians and legitimates their unequal treatment. Proposition 8 perpetuates the stereotype that gays and lesbians are incapable of forming long-term loving relationships and that gays and lesbians are not good parents."
10. "The gender of a child's parent is not a factor in a child's adjustment. The sexual orientation of an individual does not determine whether that individual can be a good parent. Children raised by gay or lesbian parents are as likely as children raised by heterosexual parents to be healthy, successful and well-adjusted."
While the theological question of LGBT marriage and ordination remains a deeply contentious one, and I am able to understand many of the various views that people hold even where I disagree with them, the civil case for LGBT marriage seems overwhelming. The only real arguments against it seem to be theological arguments with the serial numbers filed off - or they're just vague threats with a background of storm clouds. While these might have some power among portions of society, I don't see how they can hold up in the harsh light of a courtroom.