6 “Your kingdom come.” To whom do we speak? And will not God's kingdom come, if we ask it not. For of that kingdom do we speak which will be after the end of the world. For God has a kingdom always; neither is He ever without a kingdom, whom the whole creation serves. But what kingdom then do you wish for? That of which it is written in the Gospel, “Come, you blessed of My Father, receive the kingdom which is prepared for you from the beginning of the world.” Lo here is the kingdom whereof we say, “Your kingdom come.” We pray that it may come in us; we pray that we may be found in it. For come it certainly will; but what will it profit you, if it shall find you at the left hand? Therefore, here again it is for your own self that you wish well; for yourself you pray. This it is that you long for; this desire in your prayer, that you may so live, that you may have a part in the kingdom of God, which is to be given to all saints. Therefore when you say, “Your kingdom come,” you pray for yourself, that you may live well. Let us have part in Your kingdom: let that come even to us, which is to come to Your saints and righteous ones.
Source: Sermons on Selected Lessons of the New Testament (New Advent)