Romans #30

These two verses raise two very important questions. First, doesn't this understanding that salvation is all of grace encourage people to go on sinning? Secondly, if salvation isn't attained by keeping the law and doing good, then what use is God's law? Why was it ever given in the first place? What is its purpose?

Paul addresses the first question in chapter 6 & the second question in chapter 7 before returning his main theme of what it means to be justified before God by grace through faith in chapter 8.
In these two verses Paul takes up the first question I mentioned. Theologians call this the question of antinomianism, which means "against the law." The antinomian reasons like this, since salvation is all of grace, then it doesn't really matter if we go on sinning or how much we sin, does it?

This is a distortion of the teaching that salvation is all of grace.

In 6:1-2 Paul gives a clear response to this distortion and then spends the rest of chapter 6 underscoring his point. Chapter 6 can be divided into 2 sections. Verses 1-14 show how a true Christian cannot go on living contentedly in sin because he is united to Christ. Verses 15-23 show that, in addition to being united to Christ, a true Christian is someone who experiences the joy and freedom of being a slave to Christ and therefore a slave to righteousness.