There is nothing in this world to which we can point to and say that is like the kingdom of God. All we can do is offer analogies of what it looks like saying the kingdom is like this… while it isn’t this… it’s like this… That’s why Jesus preferred to talk about the kingdom in parables in a way talking about another world, which is what the kingdom is, by referring to ordinary things in this world. George MacDonald’s illustration is a wonderful tool to help in this endeavor:

Imagine for a moment that the room in which you currently reside is the only room in the whole world and the people with whom you occupy that room are the only people in the world; there are no windows or doors in your room, hence you have no concept of anything outside your little world. Indeed, the word outside doesn’t even exist in your language. You will of course be forgiven in such a situation for believing that your room and the people with whom you occupy it were the entire universe and we learn those of us who occupy this room that there are certain rules which govern life in our room: rules like only the strong survive and look out for number one.

Throughout life, we’ve learned in this room that people only have worth if they have value to us; therefore, the sick and the old and the disabled have no worth. This room has taught us we only need to keep promises as long as they’re convenient to do so; these are the rules that govern life in this room. However, unbeknown to us, there is another floor above our room with other people living other lives by a very different set of rules. We’re not aware of them because we have never been outside our little world but they are there nonetheless.
Now, suppose a hole was torn in the ceiling of our room so that for the first time you were to become aware of this other world just above. And suppose some in our world began to call up to the people in the other room interacting with them learning all sorts of strange and wondrous things. Things, which are utterly inconceivable in our room and indeed you, discover to your amazement that people in the room above live their lives according to a very different set of rules. In the room above, the poor are not regarded as a drain on the system, but are precious and prized; the old and the sick are honored and valued rather than warehoused or discarded. In this world if one makes a promise, one keeps it, even when it’s inconvenient or difficult and in this world it’s OK to suffer for doing the right thing.

Imagine then some in the world below begin to find themselves strangely drawn towards the world above. Indeed, a few were so captured by that world and its new way of living that even though they are still in the world below they start to think of themselves as really belonging to the world above. Though they are still in your world, they are no longer of your world. The knowledge of the room above having broken through into their world has changed them forever. To be sure, the whole ceiling has not yet been torn away, but already we’ve started to see a whole new world with a whole new way of living life. That’s what Jesus meant when He described an in breaking of the kingdom of God in His life and ministry creating a new community of people still in the old room, but living as though they already belong to the room above. He called that community the church: the community of the called, the community of those who have seen it and have been captured by it, and can never again be the same. The love of God changes us and after that supernatural encounter we should never be the same. That’s why we are in this world, but not of it. The kingdom of God awaits those who are called by His name and do what is right in the eyes of the Lord; while also remembering what we do for the least of them, we do for the Master.