I've mentioned before that slavery is a problem, and that the books of the major monotheisms don't have a single verse against slavery, anywhere, within them -- (see my article on slavery and the Bible, or my article on slavery and the Koran).
TED.com has a ton of high quality and short-and-to-the-point talks on a wide range of topics -- I recommend the site and the videos. One of the speakers, Kevin Bales, gave a recent TED talk on the problem that modern slavery still holds on the world.
Slavery is still a problem today. The International Labour Organization (A UN specialized agency which seeks the promotion of social justice and internationally recognized human and labor rights) says:
"At least 12.3 million people around the world are trapped in forced labour."
If you engage in religious debates often, you will find that there are a large number of people who think the question of whether slavery is morally wrong is difficult to figure out. They will insist that they (and everyone else) needs to be told the answer by their Holy Book. That fact by itself isn't so strange, but combined with the additional fact that most of those same people seem to have figured out that slavery is morally wrong -- and they hold this position with conviction. If a person thinks that the Bible or Koran needs to be consulted to figure out whether slavery is morally wrong, he wouldn't think that slavery is wrong.
A person who is confronted with the facts above and who are completely wedded to the idea that morality comes from the Word of God, there is quite a bit of cognitive dissonance that he has to work through.
There are a number of common responses a person who is backed up against this wall reaches for -- most recently a person disagreed with me, saying that there were verses in the Bible that spoke directly against the evil institution of slavery. We happened to be in a location where we (and about 5 other people who were participating in the discussion) were going to be for the next hour. So I said, "Ok, you are flat out contradicting what I just claimed: that there isn't a single Bible verse that speaks against slavery, and I said it because I've researched the question and I think that what I just said is completely true -- but I'm 100% willing to be corrected and would be grateful to learn something new today. Since we're all going to be here for a while, and you have your laptop and a fast internet connection, please take some time to figure out precisely whether I'm wrong or not."
The person brought up two verses for consideration.
1. Everyone is equal in God's eyes and
2. Slave traders are a problem.
As many of you as were baptized into Christ have clothed yourselves with Christ. There is no longer Jew or Greek, there is no longer slave or free, there is no longer male and female; for all of you are one in Christ Jesus.
The parallel structure could not make the point more obvious. If you are baptized into Christ, does God care if you are a Jew or a Greek? No. How about whether you are male or female? God does not care at all. What if you own slaves, or are owned as a slave? God doesn't care. The whole point of these verses is to show that there is no moral difference between different ethnicities, genders, or classes (include master/slave classes). A person who brings up this verse in support of the notion that God has a moral problem with the institution of slavery has brought evidence to the contrary to the table.
What about the slave-traders verse?
1 Timothy 1:9-11
This means understanding that the law is laid down not for the innocent but for the lawless and disobedient, for the godless and sinful, for the unholy and profane, for those who kill their father or mother, for murderers, fornicators, sodomites, slave-traders, liars, perjurers, and whatever else is contrary to the sound teaching that conforms to the glorious gospel of the blessed God, which he entrusted to me.
Here we have a potential anti-slavery bible verse. The condemnation is of slave-traders in particular, which is a weird thing to have a problem with if your target is the owning of people as property as an institution. Turns out, in context this verse is specifically speaking out against people who kidnap non-slaves and sell them into slavery.
I prefer just turning a few pages later in the same letter by the same author to highlight exactly what he thinks of slaves.
1 Timothy 6:1-5 (NRSV)
Let all who are under the yoke of slavery regard their masters as worthy of all honor, so that the name of God and the teaching may not be blasphemed. Those who have believing masters must not be disrespectful to them on the ground that they are members of the church; rather they must serve them all the more, since those who benefit by their service are believers and beloved. Teach and urge these duties. Whoever teaches otherwise and does not agree with the sound words of our Lord Jesus Christ and the teaching that is in accordance with godliness, is conceited, understanding nothing, and has a morbid craving for controversy and for disputes about words. From these come envy, dissension, slander, base suspicions, and wrangling among those who are depraved in mind and bereft of the truth, imagining that godliness is a means of gain.
No need to go into a detailed argument at all -- speaks for itself fairly well, doesn't it? Treat your masters well -- especially if your masters are Christian. Of all the people to encourage how to treat the other, it's interesting that the slaves are being told to treat the masters well, isn't it?
After about a half hour more of searching the person I was talking to conceded that she couldn't find the verse that she was thinking of -- and Google couldn't find it either.
Slavery just isn't a historical problem. It's a modern problem -- and an example of where getting your moral convictions from the Bible or the Koran would leave you with a gaping whole where your moral outrage is supposed to be.