Here we have a sure and strong word of comfort: “Let marriage be held in honor among all, and let the marriage bed be undefiled.”  Hold fast to that, those of you who are married.

St. Augustine writes in one place concerning married people, that even if one of them is somewhat weak, etc., he should not be afraid of the sudden and infallible Day of the Lord; even if the Day of the Lord were to come in the hour when man and wife were having marital intercourse, they should not be afraid of it. Why is this so? Because even if the Lord comes in that hour he will find them in the ordinance and station in which they have been placed and installed by God.

Now, since this is so, nobody, no mandate of emperor, pope, or bishop, shall stand in my way and prevent me. I am content that I have a gracious God, who is pleased with this ordinance, and who also regards me and blesses and protects me. Who made them so bold and who commanded them to tear down this glorious ordinance of God?… (“Sermon at Marriage of Sigismund von Luindenau, 1545” Luther’s Works, v. 51, p.362-363)

Now we know what the marriage estate is, namely, the creation and ordinance of God, and what is essential to it, namely, a man and a wife. Therefore it should also be considered pure by all men. And if the pope were a Christian, he, too, would hold the marriage estate to be holy and pure. But since he is not a Christian, but the Antichrist and the devil himself, he despises holy matrimony and considers it unclean. But God, who ordained and appointed and blessed the marriage estate, honors marriage. Therefore, we, who are Christians and children of God through faith in Christ, should also honor, uphold, cherish, and esteem the marriage estate. And it should also be kept pure by all; which means that no whore nor adulterer should be found among you, but rather each of you should have his own wife. Moreover, it was for the sake of the marriage estate that God gave us the fourth commandment and made it the first commandment following the first table, thereby declaring that he wants marriage to be upheld and honored, for he says, “Honor your father and your mother, etc.” [Exod. 20:12]. Why should I honor father and mother; after all they lead a carnal life? No, the life father and mother lead is an honorable and godly life. Just as it would be a dishonor for you, if you were born of a whore out of wedlock, so it would be a dishonor if parents lived together unmarried. Therefore to be married is honorable and pleasing to God. But if for a time you have lived outside of this state in concubinage and led a life of fornication, ah, then stop it and repent, enter into marriage and henceforth live a married and godly life. Then you will be doing the right and Christian thing. (“Sermon at Marriage of Sigismund von Luindenau, 1545” Luther’s Works, v. 51, p.364)