In flaming fire - This is a circumstance which is not noticed in the account of his appearing in the parallel place in 1 Thessalonians 4:16. The object of the apostle here seems to be to represent him as coming amidst vivid flashes of lightning. He is commonly described as coming in clouds, and to that common description there is here added the image of incessant lightnings, as if the whole heavens were illuminated with a continued blaze.
Taking vengeance - Margin, “yielding.” Greek, “giving. The word “vengeance” is used in the sense of punishment, for there cannot be in God what literally corresponds with the passion of revenge; compare the notes on Romans 12:19.
On them that know not God. - On all who are strangers to him; that is, who are living in pagan darkness, or who, having heard of him, have no practical acquaintance with him.
And that obey not the gospel of our Lord Jesus Christ. - Who do not embrace it, and practice its precepts in their lives; compare the notes on Romans 2:9.