St. Paul introduced, in the first century, a three-tiered hierarchy of slave relations—heavenly master (top), earthly master (middle), enslaved (bottom). “He who was free when called is a slave of Christ,” he testified in 1 Corinthians. “Slaves” were to “obey in everything those that are your earthly masters, not with eyeservice as men-pleasers, but in singleness of heart, fearing the Lord.” In a crucial caveat in Galatians 3:28, St. Paul equalized the souls of masters and slaves as “all one in Christ Jesus.”
Paul does not say anything about souls here. This is reading into Paul what he is not saying. That doesn't mean that the Puritans didn't use Paul this way though.
