Dr. Luther’s Small Catechism lesson for the week of December 28, 2014:
[III] THE LORD’S PRAYER
IN THE PLAIN FORM IN WHICH THE HEAD OF THE FAMILY
SHALL TEACH IT TO HIS HOUSEHOLD
THE THIRD PETITION
“Thy will be done on earth as it is in heaven.”
What does this mean?
Answer: To be sure, the good and gracious will of God is done without our prayer, but we pray in this petition that it may also be done by us.
How is this done?
Answer: When God curbs and destroys every evil counsel and purpose of the devil, of the world, and of our flesh which would hinder us from hallowing his name an prevent the coming of his kingdom, and when he strengthens us and keeps us steadfast in his Word and in faith even to the end. This is his good and gracious will.
 Tappert, T. G. (Ed.). (1959). The Book of Concord The Confessions of the Evangelical Lutheran Church. (p. 347). Philadelphia: Mühlenberg Press.