The message of the kingdom is a central theme, if not the central theme, in the ministry of Jesus as recorded by Luke. Jesus "went on through cities and villages, proclaiming and bringing the good news of the kingdom of God" (Luke 8:1). And because it was central for him, it was central for the disciples, "And he called the twelve together, and gave them power and authority over all demons, and to cure diseases, and he sent them out to proclaim the kingdom of God, and to heal" (Luke 9:1).
So, it is no surprise that, when asked how to pray, Jesus would instruct his disciples to pray this way,
"Thy Kingdom Come."
Tim Keller comments:
Augustine says God is reigning now, but just as a light is absent to those refusing to open their eyes, so it is possible to refuse God's rule. This is the cause of all our human problems, since we were created to serve him, and when we serve other things in God's place, all spiritual, psychological, cultural, and even material problems ensue. Therefore, we need his kingdom to "come."
Calvin believed there were two ways God's kingdom comes - through the Spirit, who "corrects our desires," and through the Word of God, which "shapes our thoughts." This, then, is a "Lordship" petition: It is asking God to extend his royal power over every part of our lives - emotions, desires, thoughts, and commitments. It is reminiscent of Thomas Cranmer's "collect" for the fourteenth Sunday after Trinity,
"that we may obtain that which thou dost promise, make us to love that which thou dost command."
We are asking God to so fully rule us that we want to obey him with all our hearts and with joy.
Luther adds also an outward and a future dimension. The reign of God on earth is only partial now, but the fullness of the future kingdom is unimaginable. All suffering, injustice, poverty, and death will be ended. To pray "thy kingdom come" is to "yearn for that future life" of justice and peace, and to ask that "your future kingdom may be the end and the consummation of the kingdom you have begun in us."