What does 1 Peter 2:18 mean?
After commanding all Christians to submit to every human authority, including emperors, kings, and governors, Peter specifically says the same to Christian servants (or slaves) about their masters. The word used here is not the Greek douli, the classic term for "slaves." Rather, it is oiketai, probably best translated as "servants." That being said, the line between servants and slaves was blurry in Peter's time. Slavery had little to do with race, as modern readers often process the idea, and more to do with economics and social class.Slaves consisted of those captured in war, those born into slavery as children, and those who had sold themselves into servitude for a set time. Some "slaves" were highly educated and served as artists, accountants, skilled craftsmen, etc. Others worked under terrible conditions (in mines, for example). Many suffered significant abuse; few reasonable legal restrictions existed about the treatment of slaves. Slavery in this era was completely normalized, and a large percentage of Peter's readers in the early Christian church were slaves and/or servants of one kind or another.
It's important to recognize here that God's commands to slaves about submission are not an endorsement of slavery as an institution. It was simply a reality of the day. As someone who was now "free in Christ" by the grace of God, how should a Christian slave live in the world? Peter insists that God's will for slaves is the same as His will for everyone under any kind of human authority: Don't make it about your master; make it about God.
This command is to demonstrate reverence for God by giving respect and submission to one's master, no matter how fair and kind or harsh and unreasonable he may be. In fact, the term translated "respect" in translations such as the ESV and NASB is phobō, from the same root word used to describe a respectful "fear" of God in verse 17. Those who are truly free aren't dependent on any human authority to determine their actions or attitudes. We submit to human authority for the Lord's sake (1 Peter 2:13) and, as Jesus did, trust our Father to provide for us (1 Peter 2:23).