5. Thus it is true, as men say, that parents could attain salvation by training their own children, even if they were to do nothing else. If parents do this by rightly training them to God’s service, they will indeed have their hands full of good works. For what are the hungry, the thirsty, the naked, the sick, the alien if not the souls of your own children? With these God makes a hospital of your own house. He sets you over them as the hospital superintendent, to wait on them, to give them the food and drink of good words and works. [He sets you over them] that they may learn to trust God, to believe in him, to fear him, and to set their whole hope upon him; to honor his name and never curse or swear; to mortify themselves by praying, fasting, watching, working; to go to church, wait on the word of God, and observe the sabbath. [He sets you over them] that they may learn to despise temporal things, to bear misfortune without complaint, and neither fear death nor love this life.
… It has been said in reference to the other commandments that they are to be fulfilled in relation to faith, the chief work. It is the same in this instance. Nobody must think that the training and teaching of his children is sufficient in itself. It must be done in confidence of God’s favor. A man must have no doubt that he is well pleasing to God in what he is doing, and he should let work of this kind be nothing else but an expression and exercise of his faith. He should trust in God and look to him for blessings and a gracious will. Without faith of this kind no work is a genuine living work: it is neither good nor acceptable. Many heathen have brought their children up charmingly, but all that is lost because of their unbelief. (Luther’s Works, v. 44 p.85, 86-87).