The Apostle Paul
2 Thessalonians 1:8BSB·traditional attribution

in blazing fire, inflicting vengeance on those who do not know God and do not obey the gospel of our Lord Jesus.

John Calvin Reformed @genevareformer

8 Who will inflict vengeance. That he may the better persuade believers that the persecutions which they endure will not go unpunished, he teaches that this also involves the interests of God himself, inasmuch as the same persons that persecute the pious are guilty of rebellion against God.

Matthew Henry Presbyterian @wholebiblehenry

Having mentioned their persecutions and tribulations, which they endured principally for the cause of Christ, the apostle proceeds to offer several things for their comfort under them; as, I. He tells them of the present happiness and advantage of their sufferings, Th2 1:5. Their faith being thus tried, and patience exercised, they were improved by their sufferings, insomuch that they were counted worthy of the kingdom of God.

Commenting on 2 Thessalonians 1:5-10

John Gill Reformed Baptist @doctorgill

In flaming fire,.... Which may either refer to Christ, who will be revealed from heaven in such a manner; and whose coming will be as the lightning, not only sudden, but glorious, illustrious, and visible; he will be seen and easily discerned; there will be such a light and flaming fire about him, which, as it will serve to make him visible, will greatly add...