Also, I want to quickly address the title's question itself. Is opposing gay marriage the same as being racist? Maybe. I certainly say that being anti-gay is the same as being racist. I also say that being against gay marriage is absolutely the same as being against interracial marriage.

After all, the Bible is definitely more explicitly against interracial marriage than it is against gay marriage.

"Ye shall keep my statutes. Thou shalt not let thy cattle gender with a diverse kind: thou shalt not sow thy field with mingled seed: neither shall a garment mingled of linen and woollen come upon thee." Leviticus 19:19

"That I may make you swear by the Lord, the God of heaven and God of the earth, that you will not take a wife for my son from the daughters of the Canaanites, among whom I dwell, 4 but will go to my country and to my kindred, and take a wife for my son Isaac.” (Genesis 24:3-4)

"Therefore do not give your daughters to their sons, neither take their daughters for your sons, and never seek their peace or prosperity, that you may be strong and eat the good of the land and leave it for an inheritance to your children forever." (Ezra 9:12)

"In those days also I saw the Jews who had married women of Ashdod, Ammon, and Moab. And half of their children spoke the language of Ashdod, and they could not speak the language of Judah, but only the language of each people. And I confronted them and cursed them and beat some of them and pulled out their hair. And I made them take oath in the name of God, saying, “You shall not give your daughters to their sons, or take their daughters for your sons or for yourselves. Did not Solomon king of Israel sin on account of such women? Among the many nations there was no king like him, and he was beloved by his God, and God made him king over all Israel. Nevertheless, foreign women made even him to sin. Shall we then listen to you and do all this great evil and act treacherously against our God by marrying foreign wo...

"The big deal is that strictures against homosexuality are rooted far more deeply in the Judeo-Christian tradition than racism ever was. Yes, slavery is found throughout the Scriptures and comes in for criticism only, at best, by implication."

This is just completely untrue.

The old testament is riddled with rules for the treatment of slaves. Exodus 21 provides instruction on how to sell your daughter into slavery, tells us when it's okay to split up married slaves, and warns us that if we beat our female slaves to death that we shall be punished (but if she lives for a day or two afterwards and then dies you're in the clear.)

The new testament isn't immune, either. There are a few passages that instruct slaves to be completely obedient to their masters. Most of these are attributed to Christ himself (Ephesians 6:5, 1 Timothy 6:1-2.)

Homosexuality is pretty clearly condemned as well but only the one time (If a man also lie with mankind, as he lieth with a woman, both of them have committed an abomination: they shall surely be put to death; their blood shall be upon them - Leviticus 20:13.) Other references are pretty vague. Still, the bible clearly condemns homosexuality but it also absolutely condones slavery (and with more frequency and vigor.)

The author's other point about slavery, that "race-based slavery — and the racism that made it possible and continues to infect ideas and institutions throughout the West to this day — receives no explicit endorsement from the Bible," is also iffy.

Leviticus 25:44-46 points out that "you may purchase male or female slaves from among the foreigners who live among you. You may also purchase the children of such resident foreigners, including those who have been born in your land. You may treat them as your property, passing them on to your children as a permanent inheritance. You may treat your slaves like this, but the people of Israel, your relatives, must never be treated this way." While it's true that...