These verses are an exhortation to this young church–who are doing well spiritually–to continue to increase in the kind of conduct that pleases God in the areas of sexual conduct and brotherly love. While the cultural context and circumstances may differ significantly from our own, there is still much here for the church today.
Paul, knowing the church in Thessalonica was experiencing affliction and persecution, sends Timothy to exhort and encourage them so that they are unmoved in their faith. Both Paul and the church were experiencing the effects of spiritual warfare such that Paul attributes their tribulation to satan. Upon Timothy's return to Paul in Corinth, he shares the good news that the Thessalonians have remained steadfast in their faith.
Paul begins chapter 2 by reminding the Thessalonians of how he and his companions came to them. They came boldly yet gently, faithfully not with error and eager to share the hope of salvation not selfishly. When among them, Paul lived above reproach and as such, the Thessalonians began to follow his example. He now urges them to walk in a manner worthy of God.