I've written on this a little bit in other places and it is a volatile topic and one that is difficult to discuss without getting emotional (for anybody).  I am writing from a philosophical point, not an emotional point.

I AM NOT "PRO-SLAVERY"; the post is to encourage the philosophical and Biblical viewpoint of calling sin "sin" and making sure that which we call "sin" is.
1) God does not regulate sin - He prohibits it.

If Scripture never tells us that an activity is sin, the burden of proof is on the one who calls it "sin".

The easiest way to prove slavery "sin" is to stand on the "golden rule".  Treat others the way you want to be treated.  If you would not want to be a slave, don't enslave others.  As a Christian...that makes perfect sense.

The next question would be:  might there be (or ever in history have been) a reason that being a slave might be better than the alternative?  Are there any circumstances that slavery would be beneficial/harmful to either the individual or the society.
2) right off hand, I can think of four different kinds of slavery  mentioned in Scripture:

• debt slavery
• kidnapping for the purpose of slavery
• prisoners of war
• punitive slavery

---Debt slavery:  If a person finds themselves overloaded with debt, they have the opportunity to work off that debt to the person owed.  They are released at the end of the time, they are free of the debt.  They are able to bail themselves out.  (that's a definition, not a judgement.)

NOTE:  I do not see this as being a good or practical thing in the society that we have today.  Looking at the "debtor's prisons" that we read about, it might have seemed a good option at the time.

SIN or not? (from Scripture only, please)?  (I'd rather have a discussion than put forth my thoughts - but would most likely play devil's advocate either way)

---Chattel slavery:  there is no justification of this act.  Slave trade was on the list of Tyre's condemnation and no matter what I might find about the other sorts of "manditory labor", the kidnapping and enslavement of a group of people - and the further keeping of their descendents in slavery is wrong.  Sin.  Condemned.  There is no justification for this.  (I believe that the preying on impoverished parents of children and purchasing them for the purpose of slavery that we see to day in parts of Africa and Asia are included in this segment.

---Prisoners of war:  three choices - dead.  refugee camp.  slave.  None of them are good choices.  (Again this is for discussion purpose and I'll gladly play devil's advocate for either side - but argue from Scripture)

NOTE:  the Geneva Convention permits the use of prisoners of war for "forced labor".  There are strict guidelines about what sort of work can be done, working and living conditions and prohibits the use of forced labor on actual military jobs.  A prisoner of war can be made to work in an agriculture setting, but cannot be made to manufacture bombs.

Using a prisoner of war for "forced labor" is not the same as conducting a war in order to get prisoners in order to get slaves (see kidnapping)

---Punitive slavery:  Sorry, but I think I could convinced to be at least a little bit in favor of this one.

California:  a "soccer mom" was loading stuff into the back of her car and was rear ended by an "illegal alien" (undocumented immigrant) - who happened to be driving under the influence of alcohol.  This wife and mother lost the use of her legs and looks forward to many months of rehab and the expenses incurred not only as part of treatment, but also with living as a person with impairments.

- instead of being shipped back to Mexico - again - after being caught driving drunk - again - what if this man were put in a place where his labor contributed to the income of the woman that he injured?

Michigan:  A man shoots and kills a cop, depriving the officer's wife and children of his love, support and income.  We now have a single mom with three kids.

- instead of being imprisoned for life, what if this man's labor went into a college fund for the children of the man he killed?

Anywhere:  a young man steals a car and wrecks it.  The insurance company pays, the owner of the car pays, the young man may lose time.

What if a person who steals property and destroys or damages it was made to work for the owner of the property in order to make restitution?

From Scripture, please?

(NOTE:  this post is only philosophical ramblings...mostly due to the continued and wearying and offensive habit of some egalitarians of comparing a Godly marriage where the husband is the leader...to chattel slavery)

What we think of as slavery (in the modern sense) fits into the "kidnapping for slavery" slot.  Race-based slavery fits into that slot.  Kidnapping and breeding of a group of people for the purpose of slavery is sin.  Condemned.  Wrong.

This  "chattel" slavery (and subsequent denial of the slave's humanity) can (in NO WAY) be justified.  The other three (especially in Scripture) have no impact on the way that the humanity of the slave (or bond-servant in some cases) was seen.  In two of the cases the "slavery" was more "manditory labor" which was brought about by the actions of the person in bondage.

Again, I am not in ANY WAY advocating for a return of the chattel slave system, a dehumanization of a race, the manditory

From an emotional standpoint:  I have no desire to be a slave or own a slave.  To my modern mind, the idea is not at all attractive.  As a Christian:  slavery is to be avoided and I think that it is sin for a Christian to seek to be a slave.