What is the kingdom of God?
The easiest way I have come across to explain what the kingdom of God is is to put it in the context of the story of all of creation:
In the beginning God made everything good. Everything pleased him and everything occupied it’s proper place. All that God made was woven together in a beautiful fabric. Then something went wrong. Disobedience was introduced and it was the fatal fall. When man fell his fall warped not only himself but all the things that God had made. Sin entered and tore at the fabric that God had woven together. We have grown up in a world that is waving like an old flag, full of rents and tears, and living in that world has lots of beauty and peace in it (because God made it good) but it also has heartbreak and pain and ugliness (because it is fallen). God is committed to the world he has made and is always at work binding it together, reweaving the torn fabric. The kingdom if God is this restoration. The kingdom of God is where the king reigns. It spreads as God reaches into the world and reorders it, reweaves it, sets right everything sin twisted.
Think about it like this: the kingdom of God is whatever happened to people when they touched Jesus.
People were healed. He sorted out the way sin had twisted their bodies.
He taught them. He told people what the kingdom of was like and how to live in it. He sorted out the way sin had twisted their minds and ideas.
The marginalized found a home with him. He sorted out the way that sin twisted society. He spent his time with both the have’s and the have-not’s.
He sorted out how sin had twisted the natural world. He calmed the seas, he cursed a fig tree and it withered. He showed that the reign of the king extends even in nature and will be restored too.
He sorted out the way sin twisted life and death. He raised people from the dead. Death is not part of the design and when the king reigns it will be ended.