1 Timothy 6:1-2
1 “All who are under the yoke as slaves are to regard their own masters as worthy of all honor so that the name of God and our doctrine will not be spoken against. 2 Those who have believers as their masters must not be disrespectful to them because they are brothers or sisters, but must serve them all the more, because those who partake of the benefit are believers and beloved. Teach and preach these principles.”
Paul is not speaking of slaves that have been kidnapped or bought and sold (1 Timothy 1:10). Paul is vehemently against such a concept. Instead, Paul is talking about household employees and how they ought to respect their employers by working excellently and lovingly. If employers are Christians, then there is a deeper relationship at work that ought to be honored.