Some passages that have been used for slavery & the subjugation of women:
[TABLE="align: center"]
[TR]
[TD="class: source"]Ephesians 5:22-24
[/TD]
[TD="class: quote"]Wives, submit to your husbands as to the Lord. For the husband
is the head of the wife as Christ is the head of the church, his body, of which
he is the Savior. Now as the church submits to Christ, so also wives should
submit to their husbands in everything.
[/TD]
[/TR]
[TR]
[TD="class: source"]Exodus 21:20-21
[/TD]
[TD="class: quote"]If a man beats his male or female slave with a rod and the slave
dies as a direct result, he must be punished, but he is not to be punished if
the slave gets up after a day or two, since the slave is his property.
[/TD]
[/TR]
[TR]
[TD="class: source"]1 Peter 2:13
[/TD]
[TD="class: quote"]Submit yourselves for the Lord’s sake to every authority
instituted among men.
[/TD]
[/TR]
[TR]
[TD="class: source"]2:18
[/TD]
[TD="class: quote"]Slaves, submit yourselves to your masters with all respect, not
only to those who are good and considerate, but also to those who are
harsh.
[/TD]
[/TR]
[TR]
[TD="class: quote"]
Leviticus 25:44-45[/TD]
[TD="class: quote"]Your male and female slaves are to come from the nations around
you; from them you may buy slaves. You may also buy some of the temporary
residents living among you and members of their clans born in your country, and
they will become your property.
[/TD]
[/TR]
[/TABLE]
I think there are plenty of other references in the Bible that are an affront to our natural understandings of right & wrong:
In the Bible's book of Deuteronomy it says that if a man marries a woman and then decides that he hates her, he can claim she wasn't a virgin when they married. At that point her father must prove she was a virgin. (How is not explained.) If he can't, then the girl is to be stoned to death at her father's doorstep.
In Leviticus, both an adulterer and adulteress, as well as someone who curses either parent, must be put to death.
If a betrothed virgin is raped in the city and doesn't cry out loud enough, then "the men of the city shall stone her to death." (Deuteronomy)
In Exodus, we see that it is permissible to sell one's daughter (but apparently not one's son) into slavery. Also in Exodus (35:2), whoever does any work on the seventh day must be put to death.
Under God's direction, Moses' army kills all the adult males, but they mercifully just take the women and children captive. When Moses learns that they left some women and children alive, he angrily says: "Kill every male among the little ones, and kill every woman that hath known man by lying with him." Throughout Bible history God is said to demand that thousands, if not millions, of men, women and children be slaughtered. And they are.
A man has an obligation to produce a child with his brother's widow. If he refuses, his sister-in-law is to spit in his face in front of the elders. (Deuteronomy 25:5-9) And in case you are Jewish, you may be familiar with the Jewish prayer: "Blessed be the God who has not created me a heathen, a slave or a woman."
Again, what differentiates the validity of the above passages with those purportedly condemning homosexuality or prohibiting their ability to marry?
I probably don't understand what you're asking, but the difference seems simple to me:
+ God neither prohibits nor commands slavery. Clearly, one could assume that it's acceptable to own slaves (assuming they are treated with Christian love), and one could assume that it's equally acceptable not to own slaves.
+ God expressly condemns homosexuality.