One of the most intriguing things in the history of the Church is how slavery was washed out of European culture--and did not gain entrance again until the eighteenth century. It was one of the great downstream effects of the Gospel upon the Roman Empire. Slavery, we recall, was up front and centre in the culture of that Empire.
Yet there is no direct denunciation of slavery in the New Testament corpus. There were no prohibitions issued. It's as if in the West no public condemnations of cigarette smoking were ever issued, but somehow the entire practice disappeared over half a millennium. Sarah Ruden writes:
. . . the early Christian church, without staging any actual campaign against slavery, in the course of the centuries weakened it until it all but disappeared from Europe. Slavery was doomed simply because it jarred with Christian feeling--the same basic circumstance that doomed it in the modern West. [Sarah Ruden, Paul Among the People: The Apostle Reinterpreted and Reimagined In His Own Time (New York: Pantheon Books, 2010), p.168.]It's rather hard to maintain the institution of slavery within the fellowship of a local Christian congregation where the slave may end up a ruling elder in the congregation and the slave-owner not. It's rather hard to endorse and participate in the slave markets when you are sitting at table next day with slaves and serving them the elements of the Eucharist.