One reason is that the aim of Jesus and the apostles was simply deeper than the reformation of a social system. They were focused on the root of the problem—the sinful state of the human heart. The fact is that the unjust system wasn’t the root of the sin of slavery, and simply changing the system wouldn’t have solved the problem in any long-term sense. The sinful human heart would just find another way to oppress others, even if the system of Roman slavery had been eliminated. So that’s what Jesus and the apostles take aim at—the human heart, whatever system it finds itself under.
