God is the only power. Any earthly powers were ordained by him. Anyone who resists is going to hell. Anyone who is doing right has nothing to fear from the authorities. That's why theocracies are such popular places to live in. Also, pay your taxes, because even though the authorities are doing god's work, god doesn't pay them.
Don't owe anyone anything except brotherly love. He gives an incomplete list of the ten commandments, then adds one: Thou shalt love thy neighbour as thyself (v. 9), which apparently allows you to fulfill the law. Except that it has never, ever happened. It doesn't matter if your neighbours live miles away or on the other side of a thin wall, everybody in the entire history of the world has had some reason to hate the people next door.
Of course no book of the bible can end without warning us that the world is going to end imminently, and Paul is winding down here, so he reminds us. He wants us to spend our last days in austere abstemiousness, no rioting, drinking, orgies, debauchery, quarreling or jealousy and instead in prayer and self-denial. You can see how if you had to stop with all that, you'd be looking forward to the end of the world.
Accept people of weak faith, don't get into arguments with them. Gotta hold onto those C&E (Christmas and Easter) christians to keep the numbers up, you know. Did you know that weak people get that way because they're vegetarians? The bible says so.
Don't judge other people's slaves, god will decide whether they'll stand up or not. Some people are holy every day of the week, others only when they have to be so.
The bible reminds us that as people, we are social creatures who neither live nor die alone. Except rather than saying we're part of a society, it tells us that we live for god. Don't judge your brother, that's god's job.
Jesus apparently told us that no food is unclean, but if there's something you don't like, that's fine, you needn't finish your broccoli. But if your eating something distresses someone else, you should stop eating it, rather than telling them to mind their own fucking business. But at the same time, defend your beliefs, because heaven won't be about food and drink, but rather about righteousness, and
peace, and joy in the Holy Ghost (v. 17).
Paul also advocates for not eating meat or consuming alcohol, lest they stumbleth (v. 21) us.