Why does Paul have such a focus on the faith of the Thessalonians?

It is important not to overlook the prominence of faith in this passage. The word faith occurs five times in 1 Thessalonians 3:1–10, showing that the new believers’ faith was at the centre of Paul’s concern for them. This concern reflects the joy and confidence expressed in 1 Thessalonians 1:8, where Paul speaks about the Thessalonians’ faith being reported all over the world. The phrase in your faith indicates that Timothy was to encourage the Thessalonians with respect to their faith. Their faith needed to be strengthened and inspired, and this was to be done through the gospel.

A wider consideration of Paul’s understanding of faith and its relation to the gospel provides significant insight into Timothy’s task in the present passage. Paul considered himself to be set apart for the gospel, so that his entire ministry was a ministry of the gospel (Romans 1:1–4); the aim of this ministry was to bring about the obedience of faith among the Gentiles (Romans 1:5). Although obedience of faith is understood by some commentators to mean the obedience which comes from faith, or believing obedience, it is more likely that Paul was referring to faith as the obedient response to the gospel, that is, the obedience which is faith. In other words, Paul’s entire ministry was a ministry of the gospel, and the response which he sought at all times was a response of faith. Ministering the gospel and responding to it in faith were not only associated with evangelism and conversion—as is sometimes thought today—but were to characterize the entire Christian life from beginning to end (Romans 1:17). Christians are those who continue to trust in Christ as he is revealed in the gospel. It is this continuing trust in Christ which produces the fruit of good works (1 Thessalonians 1:3 cf. Galatians 3:3–6).¹

With this insight into Paul’s conception of gospel ministry and the response of faith, it is easy to understand why he was so concerned about the Thessalonians’ faith. If they relinquished their trust in Christ, they would cut themselves off from the saving power of God. Therefore, Timothy had to travel with all haste to Thessalonica to strengthen and encourage them in their faith.