Tony - I didn't list every mention of slavery, I only picked a large number that either tacitly or implicitly approve of slavery (which at the time is to have the effect of recognising it as both legal and morally acceptable - the latter point being the basis for legality in the view of many, such as some arguments put forth in this thread).
I agree that taking every single chapter and verse is pointless and certainly some of the references I mentioned are not as strong on the primary point.\
But let me take just three that specifically approve of slavery:
Leviticus 25:44-46
As for your male and female slaves whom you may have: you may buy male and female slaves from among the nations that are around you. You may also buy from among the strangers who sojourn with you and their clans that are with you, who have been born in your land, and they may be your property. You may bequeath them to your sons after you to inherit as a possession forever. You may make slaves of them, but over your brothers the people of Israel you shall not rule, one over another ruthlessly.
Here, we are told that slavery is fine, that slaves are possessions forever, so long as you exclude Israelites. That's very clear. It mentions buying them, it mentions males and females, it says foreigners born locally are OK, it says they are possessions forever and can be passed down to your sons.
Ephesians 6:5
Slaves, obey your earthly masters with fear and trembling, with a sincere heart, as you would Christ,
Explicitly telling slaves to obey their masters.
Exodus 21:20-21
“When a man strikes his slave, male or female, with a rod and the slave dies under his hand, he shall be avenged. But if the slave survives a day or two, he is not to be avenged, for the slave is his money.
It's OK to beat your slaves, just not kill them. The slave is money. Clearly, there is no moral or legal objection to slaves, just to killing them (or not hurting them so badly that they die within 2 days - if it takes longer, it's OK...).
And a bonus one:
Titus 2:9-10
Slaves are to be submissive to their own masters in everything; they are to be well-pleasing, not argumentative, not pilfering, but showing all good faith, so that in everything they may adorn the doctrine of God our Savior.
Be a good slave in order to support the doctrine of God. It's far from being ambiguous or unclear.
And as a double bonus, Peter tells is that even unjust masters are OK:
1 Peter 2:18
Servants, be subject to your masters with all respect, not only to the good and gentle but also to the unjust.
The bible is NOT a source of absolute morality. It meanders all over the place, it represents the reality of the cultures and politics of the time. It represented the will of the majority of the power (not the people, since they were not empowered generally). It is an authoritative morality.
And as a final, triple bonus (because seriously, there's just too many to pass up):
Exodus 21:1-36
“Now these are the rules that you shall set before them. When you buy a Hebrew slave, he shall serve six years, and in the seventh he shall go out free, for nothing. If he comes in single, he shall go out single; if he comes in married, then his wife shall go out with him. If his master gives him a wife and she bears him sons or daughters, the wife and her children shall be her master's, and he shall go out alone. But if the slave plainly says, ‘I love my master, my wife, and my children; I will not go out free,’ ...
It specifically says "rules that you shall set before them". It's prescribing what the law should be.
Honestly, if that's not legalising or providing a morality guide as to the acceptability of slavery, in chapter and verse in the bible, then I think you're reading a different book.
As your analysis of my argument to N80. No, that's not what I said. What you are describing is moral relativism (an extreme version). My point about authoritative morality is that it carries the weight of the society and if someone acts against that (some criminal activity) then I am able to appeal to the authoritative morality of society to prosecute the guilty party.
Moreover, this is EXACTLY what happens in the real world. You don't get to go to court and say "The bible says I can buy Hebrew slaves so long as I set them free after 7 years and the bible is the word of God and therefore an absolute morality that you must accept". Society says that's bollocks and you can't have slaves and so the authoritative morality, which is empowered by society, is the relevant guide. Similarly, you don't get to say "I have a natural right to liberty and therefore you cannot gaol me for breaking a law". Well, you can say it, but society rejects it - your claim of a natural right is nothing more than a claim (I'm using "you" in a generic sense here, for clarity). The only effective authority is society, hence authoritative morality (being neither relative - it's not individual and it has inertia) and is not absolute because it can change.