As I thought about this question, I realized that a possible answer lies in the type of kingdom Jesus established. Jesus came in the midst of a world that had much experience with kings. Kings who established their kingdoms by overthrowing others. Kings who ruled by force and fear. Jesus came to inaugurate a kingdom based on love, a kingdom begun by a king who submitted to a cruel execution at the hands of the Roman empire. Jesus kingdom later turned that empire upside down. By love.
When you think about it, our world really isn't that much different than the Roman world in the first century. We elect our leaders, but how many of us obey the laws of our land because we love them. For the most part, people obey the law because they don't want to face the consequences of breaking that law. Just notice all the brakelights that come on when drivers on the highway see a state trooper on the side. Most people live lives full of fear. They fear the opinion of others. They fear the future. They fear being seen as they really are. There is force as well. The force of public opinion, the force of things that control us, the force of religion dictating how they live their lives.
As the early Christians did, we have a message that can free folks from their chains of fear and force. We are part of a kingdom, economy, world, family (whatever you want to call it), in which love rules. The reason we are in this is the love of Christ for us. Because Jesus loves us, we love. We love the Father, and we love his children. We also love those around us. We do what we do because of love. It is love that shows the world around us that we belong to Jesus, not the force of our moral or theological arguments. It is love that makes us different, not a set of behavioral rules. It is love that takes us to serve the least of these rather than expect them to come to us. It is love that lets us forgive when everyone else says we should get our revenge. It is love that allows us to lay down our lives for others when the world tells us to look out for number one. Love is the foundation of Christ's kingdom, and it is by love that his kingdom will conquer.
"Dear children, let us not love with words or speech but with actions and in truth." (1 John 3:18)