"in flaming fire taking vengeance on those who do not know God, and on those who do not obey the gospel of our Lord Jesus Christ" (2 Thessalonians 1:8).
Obey - to hearken to a command, i. e. to obey, be obedient unto, submit to (Thayer's).
Gospel - the good news of Christ has three facets: facts to believe, commands to obey, and promises to receive.
Lord Jesus Christ - His good news is the best news - the forgiveness of sin!
Believe His gospel. Obey His gospel. Receive the promises of His gospel.
Jason Cicero