What is the kingdom of God? It’s a simple question, yet if I were to ask that same question to a hundred theologians I would likely get a hundred different answers. The kingdom of God is not some sort of ancient or obsolete doctrine that no one has ever heard of. Rather, it is something we hear about all the time as a fundamental component of Jesus’ teaching and a primary theme throughout sacred Scripture. Although few would admit it, when most Christians think about the kingdom of God, their minds are strained to conceive of anything beyond some ethereal notion of mustard seeds, lost coins, different soils, and undefined future bliss.
However, when it comes right down to it, the kingdom of God should be more simple to define than just about any other theological term. It’s quite plain really: God reigns. Or, to say it another way: The kingdom of God is the omnipotent rule and sovereign reign of Almighty God over all things, the inauguration of which came with the birth, life, death, resurrection, and ascension of Christ Jesus and the fullness of which is yet to come.
Nevertheless, while it is important to have a good, biblical answer to the question, what is the kingdom of God? it is just as important to have an honest answer to the question, whose kingdom do you serve? These are the questions that are at the very heart of the Sermon on the Mount: Are you the king of your own kingdom? Are you the self-appointed potentate of your own, private little empire? You may answer with a hearty no, but does your life demonstrate that you are a servant of God or a servant of self? We all certainly want to be part of the kingdom, but most Christians want to serve the kingdom on their own terms.
As divinely appointed citizens of the kingdom of God we are foreigners in the kingdom of this world. We are real characters in the real story of redemptive history in real space and real time who have been summoned to follow the King of kings as servants, saints, and soldiers - coram Deo, before His face, in life and in death. Augustine understood this well: “We want to reach the kingdom of God, but we don’t want to travel by way of death. And yet there stands necessity saying: ‘This way, please.’ Do not hesitate, man, to go this way, when this is the way that God came to you.”