The Old Testament largely treats slavery as it does other parts of the so-called "Problem of Evil": Being enslaved was just a fact of life for some people. An exception is that Israelites should NOT be enslaved, but enslaving Gentiles was OK:
1 Kings 9:20-21 said:
All the people who were left of the Amorites, the Hittites, the Perizzites, the Hivites, and the Jebusites, who were not of the people of Israel—their descendants who were left after them in the land, whom the people of Israel were unable to devote to destruction—these Solomon drafted to be slaves, and so they are to this day.
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And I must take issue with the idea, implicit in this thread, that Americans abolished slavery BECAUSE they were Christians.
First note that there were wise and benevolent rulers in Asia and elsewhere who had abolished slavery -- at least temporarily -- long before the time of Jesus the Nazarene.
But more importantly, the Enlightenment and the Enlightened Founding Fathers, at least in the North, who set the young U.S.A. on its path were NOT Christians, at least in any normal meaning of the term.
Christianity had nothing to do with it.
I say it did. Specifically, by virtue of the fact that America was overwhelmingly Christian, most Christians did NOT own slaves, and the democratic (majority) conviction to end slavery drove the political and miilitary actions taken to end it.
America was overwhelmingly Brunette in hair color. Should we say that Brunettes freed the slaves?
Many or most of the Founding Fathers, especially in the North, were Unitarians or Deists or paid lip-service to Christianity without believing its fundamental tenets. George Washington did not take Communion as an adult; and in his speeches he spoke of "Great Author" rather than "God," and so on. John Adams rejected the divinity of Jesus Christ and the Trinity, notions he described as ''incomprehensible.'' Thomas Jefferson was a Deist; in fact all six of the first six U.S. Presidents seem to have been Deists or Unitarians (if they thought about religion at all). During the time immediately prior to the Emancipation, Thoreau and Emerson were leading Northern intellectuals; they were not orthodox Christians. Thomas Paine wasn't a politician so didn't need to pay "lip-service" to Jesus:
Thomas Paine said:
The most detestable wickedness, the most horrid cruelties, and the greatest miseries that have afflicted the human race, have had their origin in this thing called revelation, or revealed religion.
This wasn't unique to the New World. Key Enlightenment figures like David Hume and Voltaire weren't Christians. Note that many non-Christians did NOT advertise their atheism or agnosticism. There was a stigma: Even today there are some countries where atheism is a crime.
So it is at best very misleading to imagine that "Christians" enlightened the U.S.A. and ended slavery. To the contrary the orthodox Christians were more common in the southern slave-holding states.
I'll post this YouTube again since it offers such a good look at American Christianity!