2 Thessalonians 1:7b-8

v7b: There is a day coming when God will judge the world in righteousness by the man He has appointed, Jesus Christ, who is the righteous judge.  This day will come when Jesus appears from heaven. "The heavens now keep him; they conceal him; but then he will be revealed and made known."

v8: The fire that will blaze out from the Lord Jesus will be "a refining fire, to purify the saints," and "a consuming fire to evildoers."  Both those who have rejected God's general revelation, who do not know God even though He has made Himself known in creation; and especially those who have rejected God's special revelation, refusing to believe and obey the gospel of our Lord Jesus, will find Him to be a consuming fire.