Theodore of Mopsuestia — on 1Thess 1:5 (COMMENTARY ON 1 THESSALONIANS)

“For you know, he says, how you came to be chosen (that is, how you arrived at faith), for you did not believe solely by means of our words. Indeed, we not only spoke but also showed wonders, great and glorious and worked by the Spirit, by which you were strengthened with regard to the things we had spoken to you. Hold on tightly to what you have learned, and don't be deflected from your course by the external things that happen to you.”