"God is just: he will pay back trouble to those who trouble you and give relief to you who are troubled." (2 Thessalonians 1:6-7)
Paul gives thanks for the Thessalonians' growing faith and increasing love, and for their perseverance and faith in all the persecutions and trials they are enduring. Their endurance is evidence of God's righteous judgment that they will be counted worthy of his Kingdom. God is just: he will pay back trouble to those who trouble you and give relief to you who are troubled. This will happen when the Lord Jesus is revealed from heaven in blazing fire with his powerful angels, to punish those who do not know God and refuse to obey the Gospel of our Lord Jesus. They will be punished with everlasting destruction and shut out from the presence of the Lord, on the day he comes to be glorified in his holy people.
The eschatological justice promised here is the pastoral foundation of Christian perseverance under suffering. Paul does not counsel the Thessalonians to pretend their suffering does not hurt, or to be indifferent to the injustice done to them. He tells them the truth: God sees it, God is just, and the day of accounting is coming. The Catechism presents the last judgment as the moment when the full truth of every person's relationship with God and neighbour will be revealed, and every injustice either repented or answered for (CCC 1039).
Brothers and sisters, God is just. He will pay back trouble to those who trouble you. This is not a call to the satisfaction of revenge but to the relief of trusting that justice belongs to God. When you are being wronged and there is no human recourse, this is the word: give it to the just God who sees everything and whose accounting is perfect. Release the judgment. He will do what needs to be done.
Lord God, you are just. We give to you every injustice we have suffered and every wrong that has gone unaddressed. You see it all. On the day of the Lord Jesus, the books will be balanced. Until then, give us the perseverance and faith of the Thessalonians, counted worthy of your Kingdom. Through Christ our Lord. Amen.