John Chrysostom

"To which end also we pray always for you, that our God may count you worthy of your calling, and fulfill every desire of goodness and every work of faith, with power." "That He may count you," he says, "worthy of calling"; for they were not called. Therefore he has added, "and fulfill every desire of goodness." Since he also who was clothed in filthy garments, was called, but did not abide in his calling, but for this reason was the more rejected. "Of the calling," namely that to the bride-chamber. …

Homily on 2 Thessalonians 3 ↗

Theophylact of Ohrid

What then, were they not called? Yes, they were. But the apostle is not speaking of that calling; for according to that one, many are called. He who did not have wedding garments was also called (Matt. 22:25), and the five virgins were also called (Matt. 25:11), but neither he nor they entered. The calling that the apostle means here is that which is confirmed by deeds, and which is properly the true calling, just as genuine faith is active faith. Therefore he adds the following. …

Commentary on 2 Thessalonians ↗

Thomas Aquinas

Then when he says, "wherefore we also pray," he adds the support of prayer, and first, he sets out what he prays; second, to what purpose he prays, at "that the name"; third, how he can obtain what he prays for, at "according to the grace." He prays for one thing on God's part and two things on our part. …

Commentary on 2 Thessalonians ↗