Paul seems pretty proud of the example of the Thessalonians. Their reputation has spread throughout the area, which was important in this early formation of the Church. The fledgeling movement needed good examples to look to, and this seems to be the people who filled that bill. The Thessalonians have corrected their theology (by turning away from false gods) and also achieved a high standard for showing love to one another. These would be the prime characteristics of the Church across the first century.