In the text, Paul gives the Christians in Thessalonica some exhortations for Christian living. He urges and exhorts them to “abound more and more.” This calls for a constant longing for improvement. There is always room for growth. Paul had given them instruction on how to they “ought to walk and to please God.” This included commandments he had given them “through the Lord Jesus.” The commandments were by the authority of Christ and needed to be treated as such.
In the following verses he narrows the Christian walk down to “the will of God, [their] sanctification,” i.e., sexual purity. Paul illustrates sanctification by showing that they were not to carry themselves in “passion of lust, like the Gentiles.” Rather, they were to be sanctified, or set apart. A Christian is not called to “uncleanness, but in holiness.”
Christians should always be cognizant of their calling. We, having answered the call, are to live different than the world. This includes abstaining from sexual immorality. Whoever this displeases should remember that, “he who rejects this does not reject man, but God, who has also given us His Holy Spirit.”