That is, among Christians, forgiveness of sins shall have no measure and no end; one shall forgive the other always and beware of taking revenge; for this belongs to God alone, and His majesty and power we should never interfere with. This the parable treats of at some length, the reasons for which we will hereafter collect and notice one after another….  For the command concerning forgiveness of sins we should never apply to kingdoms of this world, in which offices and persons are not alike, but where one has always power and command over the other. Here malice is not to be tolerated nor are people to be allowed to do what they please; but misconduct must be punished and people must be admonished to live honorably and righteously.

It is not designed here to teach that a father should forgive his children everything and over look their rascality. He should punish, and for give nothing. So master and mistress and the temporal magistrate should not forgive their servants and subjects their misdemeanor, but punish them. For it is the wicked habit of the world to grow worse and worse the more its transgressions are overlooked; and if children do not want to be trained by father and mother, they must be trained by the executioner, who has to put an end to their wantonness.

Therefore this command does not pertain to the kingdoms of this world, where persons and offices are not alike, as was said before, but to the kingdom of heaven, in which we are all alike and have but one Lord, who is to be enjoyed by all. This “kingdom of heaven” begins here on earth, and is otherwise called the Christian Church on earth, in which God reigns by His Word and Spirit.  (Luther’s House Postil, Sermon for the Twenty-Second Sunday after Trinity, Volume 3, p. 864)

We should therefore follow the example of the nobleman and apply to Christ for counsel and help in all our troubles. It is an easy matter for Him to help us in our distress; He needs but to speak the word and we are delivered. He is besides very willing to help us. The nobleman is in great haste and wants to avoid every delay, but the Lord is in still greater haste, and is not willing to leave the son of the nobleman in danger, until He and his father could reach him, but heals him at once even at a distance, and at the very moment when He said to the father: “Go thy way, thy son liveth.” Thus the Lord Jesus is no doubt willing to help us, if in all confidence we ask Him. He was sent upon earth for the purpose of delivering us from sin, death and the tyranny of the devil, and to translate us into the eternal kingdom of God. For this purpose the Father, our merciful God in heaven, has sent Him, and for this purpose alone did He come.

Whoever therefore desires and seeks help against sin and death, shall surely find it, as we here learn from the nobleman, who merely sought bodily help. How much more willing will not the Lord be to help us out of a far greater danger and when we are in far greater need of His help when our eternal salvation is at stake? (Luther’s House Postil, Sermon for the Twenty-first Sunday after Trinity, Volume 3, p. 855)

Therefore whenever you hear of the kingdom of heaven, you should not merely gaze up to heaven, but look around you upon the earth and seek it among the people, in the whole world, where the Gospel is taught and Christ is believed in, and the Sacraments are properly used. The “kingdom of heaven,” in plain language, is the kingdom of Christ and the kingdom of the Gospel and of faith.

For wherever the Gospel is there Christ is also. And where Christ is there is the Holy Ghost also and His kingdom, the true kingdom of heaven. And all who have the Word and Sacraments and believe and remain in Christ by faith are heavenly princes and children of God. All that remains to be done is that God remove the partition which still separates us, that is, that we die, then all will be heaven and salvation.

Learn to understand then, in the first place, that the kingdom of heaven is the kingdom of our Lord Jesus and is to be found wherever the Word and faith are. In this kingdom we have life in hope and are, according to the Word and faith, cleansed from all sin and delivered from death and hell, notwithstanding the old Adam and the corruption of the flesh. The old Adam has not yet been destroyed and the sinful flesh has not been put away; this must yet be done, then there shall be nothing but life, righteousness and salvation. (Luther’s House Postil, Sermon for the Twentieth Sunday after Trinity, Volume 3, p. 843)