Peter writes to Christian slaves. In the late first century AD, when the Christian church spread from Palestine into the larger Roman Empire, a greater and greater percentage of the church was slaves. In the ancient world slaves were any color. Masters thought up excuses why it was allowable to enslave another, but at least they didn't create the most laughable and tragic excuses, reasoning that it was okay to enslave a person of a different color.
Slaves were a legal commodity, bought and sold. Some were born into slavery, others were captured in war, and some sold themselves into slavery to pay their debts. In the first century AD, when Peter writes, about a quarter of the people in the Roman Empire were slaves.
Another difference between ancient Roman slavery and what the US so recent…