Despise. Or, “disdain,” “be disrespectful.” Paul contends that if pagan “masters” are “worthy of all honour,” how much more respect should be given the “believing masters.”
Do them service. Because these slaves were Christians, a greater responsibility rested upon them. The pagan slaves and masters would now be able to judge the difference in honesty and respect that Christianity would make in a converted slave. But if the Christian slaves showed less respect than the non-Christian, the gospel would accordingly be judged worse than paganism, and effective evangelism would be made more difficult, if not impossible.
Partakers of the benefit. That is, the believing master will benefit by the Christian slave’s services.
These things. Paul refers to his counsel regarding the position of slaves in the Roman Empire.