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)