For crying out loud, FRiend, are you going to blame the Bible because Jews didn't always follow its commandments?
What's up with that?
The Bible is quite clear and consistent in opposing "slavery" for God's people, and this is the concept you must, must grasp or you'll be forever confused.
Yes, it recognizes that slavery is sometimes necessary, even amongst Israelites, but it requires that slaves not be mistreated and must be released after seven years (see Exodus 21).
That requirement alone makes it not real "slavery", but an employment contract -- i.e., to pay off debts.
If you wish to see an actual example of how this worked in practice, try Jeremiah chapter 34.
The short of that story is that Jews knew perfectly well what God required, and when they really, really needed His help, were willing to do it.
By the way... if you love history as much as I do, then compare the story of Jeremiah 34, where Jews in extremis free their slaves to win God's favor, contrast to that of Carthaginians in precisely the same predicament, who offer up to their god (Baal?) what he wanted most -- they kill their children.
So don't tell me the Bible doesn't know right from wrong, FRiend.
If you live in or traveling to the Atlanta area be sure to visit Sweetwater State Park located west of Atlanta. It contains ruins of a cotton mill destroyed during the Civil War.
In July 1864 Union forces reached the mill. The mill was burned down and civilian mill workers (only women and children) were arrested and the women charged with treason. Eventually they were sent North, most to Indiana. Few returned to Georgia.
http://en.wikipedia.org/wiki/Sweetwater_Creek_State_Park