Paul's efforts here reflect his pattern of planting churches in strategic cities.Thessalonica had a large Jewish population and at least one synagogue. Acts 17 mentions three Sabbaths, but it's likely that Paul was in Thessalonica a bit longer.
The Thessalonians learned how to live the Christian life by observing and imitating Paul.
They in turn became a model to the believers in Macedonia and Achaia (vv. Paul gave them an example of holding to the word despite suffering.
This may be a reference to the opposition he experienced while in Thessalonica and later in Berea.
By following Paul’s example, the Thessalonians became imitators of Christ and channels of God’s love.
Paul may have stayed several more months in Thessalonica, ministering among the Gentiles.