In the first part of this chapter, Paul teaches Christians to obey rulers who govern them. At that time, ungodly Roman rulers governed the land. (See: [[rc://en/tw/dict/bible/kt/godly]])
When Paul teaches about obeying rulers, some readers will find this difficult to understand, especially in places where rulers persecute the church. Christians must obey their rulers as well as obey God, unless the rulers do not allow Christians to do something God explicitly commands them to do. There are times when a believer must submit to these rulers and suffer at their hands. Christians understand that this world is temporary and they will ultimately be with God forever. (See: [[rc://en/tw/dict/bible/kt/eternity]])
This is a complex issue. "Flesh" is possibly a metaphor for our sinful nature. Paul is not teaching that our physical bodies are sinful. Paul appears to be teaching that as long as Christians are alive ("in the flesh"), we will continue to sin. But our new nature will be fighting against our old nature. (See: [[rc://en/tw/dict/bible/kt/flesh]] and [[rc://en/tw/dict/bible/kt/sin]])