Paul answers his question: "So do you think we should continue sinning so that god will give us even more grace?" He says "By no means!" then he goes on to write about what happens within every baptized believer. He states that in Baptism we are connected to Christ in his death...the Old Adam dies...and the covenant with sin is severed.
It is vital for us to understand this because we can only become covenanted with a new "spouse" when the old covenant is severed by the death of one of the partners in the covenant.
Having the covenant with sin severed,we are no longer under sin's control. We also are able to establish a new covenant with Christ. To continue to sin AFTER becoming covenanted with Christ greatly dishonors Christ.
In this new relationship, we continue to have enemies which "war" against us to pull us away from Christ. These enemies are: the devil, the world, and our own flesh. Paul writes about his own struggle with his flesh in chapter 7.