The relationship of a slave to his master must be “respectful submission” (1 Peter 2:18-19). The word translated “be subject” or “submit” (ὑποτάσσω) carries more negative connotations in English than in Greek. The word has the sense of being subordinate to someone or something for legitimate reasons. This is the same word he used in 2:13 to command the believer to submit to the government. In this case, a government official has been appointed to an office that has some authority, so an honorable person obeys that authority.
This is the word regularly used for the relationship of the slave and master. A slave is subordinate socially and legally in the Roman world to the master and must obey the commands of the master. Slaves did not obey everyone’s orders, but those of their master.
In the Roman world, slavery was often different than slavery in a modern sense. While it could be just as cruel and harsh, many slaves were well treated. Slaves were often educated and given responsibilities that were far beyond the modern, Western idea of a slave. In fact, slaves were the backbone of the Roman economy, the wealthy never worked since they had people working for them (the slave). Slaves were sometimes compensated for their work and could look forward to being set free. In fact, some slaves refused to be set free since they were more socially advanced as a slave of a wealthy, well-placed citizen that as a free (but poor) individual.
In addition, Peter uses the word “household slave” (οἰκέτης). This might be understood as a domestic servant rather than a “field slave.” He is not talking about the slave who is laboring in the salt mines, or being whipped in the fields, but the slave who has responsibilities in the household and is often treated as though they are part of the household.
Peter adds “with all respect.” It is possible for a slave to obey, but not respectfully. The Greek here is not “with all due respect,” but literally “in all fear” (φόβος). Fear is one of those words that can mean “for fear of getting a beating” in this context, or it can mean out of respect for the social standing of one’s master.
All three members of the household are told to act with respect (slaves, wives and husbands). This mutual respect is a subtle counter-cultural maneuver in the Greco-Roman world where a husband/master would not really have to respect their wife or slave.
The Christian slave is to submit to their master whether they are good and gentle, or unjust. As with any master/slave relationship, it is possible that a master could be unjust and cruel. The same is true for a boss/employee relationship (good boss vs. bad boss). However, the attitude of the slave ought not to depend on the personality or behavior of the master, they always are to be obedient and respectful regardless of how they are treated.
Although some disrespect is “socially acceptable” for a non-believing slave, Peter’s point here is that the Christian slave must respect their master more other slaves because a Christian slave is a “stranger and alien” in this world. But this sort of humble submission is seems rare in modern, western Christianity. Perhaps this is a result of affluent Christians who are quite at home in this world – how do we get back to Peter’s ideal of living out a Christian life that treats non-Christians with respect so they might honor God as well?