Ephesians 6:5

(6:5,6) "Slaves" were so for any number of reasons. They might have been drawn into slavery by debt, or by an act of war, or by purchase. This is not an endorsement by Paul of the existence of slavery, but of recognition that the condition was common and that the follower of Christ was likely to come from the ranks of slavery. If that happened to be the case, one was none-the-less under obligation to Christ to serve in their station of life in a manner consistent with the intent of their Lord Jesus.