2 “If you buy a Hebrew servant, he is to serve you for six years. But in the seventh year, he shall go free, without paying anything. 3 If he comes alone, he is to go free alone; but if he has a wife when he comes, she is to go with him. 4 If his master gives him a wife and she bears him sons or daughters, the woman and her children shall belong to her master, and only the man shall go free.
So a Hebrew man could sell himself into slavery, or sell his children, or be enslaved because he couldn't pay a debt. The Law was opposed to illegal enslavement of Hebrews, not to enslavement as such.
The tone of the discussion about slavery throughout the OT, and for that matter the NT, is matter of fact and non-judgmental.
And of course the Law with regard to foreign slaves was essentially the same as that of the nations around them. Anything goes.
I really, really wish this was not the case, and I could say the Bible is as non-supportive of slavery as it is non-supportive of racism. But it says what it says, and that is that slavery was such a fact of life that none of the Bible writers considered abolishing it, anymore than they considered abolishing air. And for much the same reason.
That said, slavery in the ancient world was in some ways less harsh than in the American South. "All men were created equal" hadn't crossed anybody's mind yet, so the line between slavery and freedom wasn't as clear. Everybody existed on a scale, with people above and below them.
Most non-slaves weren't really free in the sense we use the term. There were intermittent conditions, and those who really were legally slaves were often wealthy, powerful and respected. See Abraham's slave Eleazar, who was his heir until his sons were born.
All women of the time existed in a condition we would consider very near that of slaves. A woman did not choose her husband, for instance, she was quite literally given, or possibly sold, to her husband.
There was no link between "race" and condition of servitude. Slaves came in all colors. So everybody knew they could be enslaved themselves. Often it was the price of losing a war or having your ship taken by pirates. To our minds it is thus totally illogical to believe men were naturally slaves, when their condition was often the result of bad luck. But the ancients just didn't see it this way.
But if you accept the proposition that all men are equal, then by definition non-equal slaves become in some sense less than men.
FRiend, I see perfectly well what your problem here is, and I think I can help clear it up.
Your problem is the definition of the word "slave".
The Bible absolutely did not mean the same thing in referring to Hebrew "slaves" as American secessionists meant referring to their "peculiar institution".
For starters, ancient Israelites could not lawfully become slaves except for specific reasons, usually to pay off a debt.
And even then, slaves had to be given their freedom after seven years.
So by our understanding of terms, that's not really slavery, rather it's a long-term employment contract with "wages" used to pay off debts.
Once the contract is fulfilled, the "slave" goes free.
In colonial times, these people were referred to as indentured servants, and indeed, in the very beginnings, that's also how African slaves were treated.
Only over time did slavery as it was known in 1860 develop, where only people of African descent could be slaves, where slaves were considered sub-human (see Dred Scott) "property", and even when gaining freedom were still subject to vagaries of laws which might re-enslave them (as was declared by the Confederate government during the war).
Note Deuteronomy 23:15 ESV:
So how is it that those who claim slavery was "no sin" cannot see that the Bible condemns both the capturing of slaves and returning escaped slaves to their masters?
If slave-holders were truly interested in Biblical views, wouldn't such verses give them pause?