From the Word
2 Grace to you and peace from God the Father and the Lord Jesus Christ. 3 We are bound to give thanks to God always for you, brethren, as is fitting, because your faith is growing abundantly, and the love of every one of you for one another is increasing. 4 Therefore we ourselves boast of you in the churches of God for your steadfastness and faith in all your persecutions and in the afflictions which you are enduring. 5 This is evidence of the righteous judgment of God, that you may be made worthy of the kingdom of God, for which you are suffering
2 Thessalonians 1:2–5, RSV
One of the chief reasons why God permits Christians to suffer on earth is to make plain the distinction between their reward and that of the ungodly. In the sufferings of believing Christians, and in the wickedness, tyranny, rage and persecution directed by the unrighteous against the godly, is a certain indication of a future life unlike this and a final judgment of God in which all men, godly and wicked, shall be forever recompensed. When Paul speaks of the tribulations and sufferings of Christians, he means to say that these afflictions are the indication of God’s righteous judgment, and a sign that you are worthy of the kingdom of God for which you suffer. In other words: “O beloved Christians, regard your sufferings as dear and precious. Think not God is angry with you, or has forgotten you, because he allows you to endure these things. They are your great help and comfort, for they show that God will be a righteous judge, will richly bless you and avenge you upon your persecutors. In this you have unfailing assurance. You may rejoice and console yourselves, believing without the shadow of a doubt that you belong to the kingdom of God, and have been made worthy of it, because you suffer for its sake.”
But it is impossible that it should continue to be, as now, well with the world and evil with you. God’s righteousness will not admit of it. Just because he is a righteous judge, things must be eventually different: the godly must have eternal good, and the wicked, on the other hand, must be punished forever. Otherwise God’s judgment would not be righteous; in other words, he would not be God. This is an impossible proposition, since God’s righteousness and truth are immutable, in his capacity as judge he must perforce in due time come from heaven, when he shall have assembled his Christians, and avenge them of their enemies, recompense the latter according to their merits, and confer eternal rest and peace upon his followers for the temporal sufferings they have endured here. Necessarily, then, he has planned a future state for Christians and for non-Christians, in either instance unlike what they know on earth.
Martin Luther and John Sander, Devotional Readings from Luther’s Works for Every Day of the Year (Rock Island, IL: Augustana Book Concern, 1915), 457–458.