In the short time Paul had been gone from Thessalonica, a number of things needed attention which he addresses. What seems obvious from his words is the presence of a problem which followed him constantly, and it needed to be addressed early on. There were always those who came in after him questioning what he taught, his motives and his position of authority. What he says in Thessalonians is similar to his defense of his ministry given in other epistles.

Paul addresses those here, before he can begin to answer some doctrinal matters. I love these parts of Paul's writings, because he not only reminds them that he is innocent of the charges, but uses it as an opportunity to remind them of what they learned and observed from Paul the servant.