This assurance and boast is given us by this text: “Let the marriage bed be undefiled among all.” But this is followed by these words: “God will judge the immoral and adulterous.”
Here is pronounced the judgment that no whoremonger or adulterer will escape God’s judgment. Here our adversaries, the enemies of marriage, must stop, and it will be no help for them to boast and appeal to their vows; for they are the real, true adulterers, who prevent marriage and forbid people to be married. But when our Lord Jesus Christ comes on the last day to judge the living and the dead, God will not judge the married, for they are in his ordinance. Oh, what an unspeakable comfort that is for all married people in their estate! How confidently they can await the glorious coming of our Lord Jesus Christ. For an apple tree or some other tree which bears its kinds of fruit will not be judged on the last day because it bears apples or is defiled by caterpillars and worms. No, for it was created by God for the purpose of bearing apples and fruit. So married people, who are wedded and bear children and live pure wedded lives, will not be judged because of this.
But the immoral and adulterous, who live outside of this state {of marriage} in defilement and impurity, such as the pope and cardinals, bishops, canons, monks, nuns, etc., who forbid marriage and themselves engage in all kinds of abominable lust and vileness and so woefully befoul the holy estate of matrimony, God will judge on that day. Then the true judgment will be made….(“Sermon at Marriage of Sigismund von Luindenau, 1545” Luther’s Works, v. 51, p.365-366)