Paul’s first letter to the church at Thessalonica is mainly a commentary on their testimony, from the perspective of the congregation (1:2-10; 2:13-16; 3:6-10) and the missionaries (2:1-12; 2:17-3:5). There is a fair amount of doctrine to glean from these first three chapters, though little compared to 4:1-5:21. Paul’s purpose with 1:1-3:13 is far from systematic.
The theme seems to be Paul’s gladness in the authentic faith of Thessalonica. Paul’s ministry in Thessalonica ended prematurely (Ac 17:1-9 cf. 1 Thess 3:4-5), preventing adequate training before he left town. Over and again in the letter, Paul mentions how grateful he is that the Thessalonians have kept the faith, because in keeping the faith amidst such unfavorable circumstances (i.e. lack of adequate theological training and general persecution) this local church has become a witness to the effectual grace of God working in their midst.
In Pauline soteriology, a string runs from God’s eternal purpose to save an individual and that individual living a life of faith in Christ. Ephesians 1:1-14: faith (v.13) is appropriated to a non-effectual position in relation to God’s activity to redeem (the fountainhead of heavenly blessings being vv.4-6). Romans 8:28-39: faith (v.28, 31) is appropriate only because God effectually saves all whom He pursues to save (vv.29-30, 31).
Now in 1 Thessalonians: faith (1:5-10) is ultimately the product of God’s electing grace (v.4). Paul is grateful to God alone for the saving faith of this church (1:3; 2:13), implying that God alone is the fountainhead of this saving faith. Consider his closing prayer: “Now may our God and Father Himself and Jesus our Lord direct our way to you; and may the Lord cause you to increase and abound in love for one another, and for all people, just as we also do for you; so that He may establish your hearts without blame in holiness before our God and Father at the coming of our Lord Jesus with all His saints” (3:11-13, emphasis mine; “may” denotes intention, not possibility; the Greek reads differently than English, but the meaning is communicated well here). Regardless of varying Christian confessions, Biblical models for prayer clearly include pleas for God’s effectual grace.
So one thing I’ve learned from 1 Thessalonians 1-3? Faith is the appropriate response to Christ, gratitude is the appropriate response to faith.