In the theology I grew up with, the kingdom of God is future, period.
We were aware that Jesus said the kingdom was near, in passages like this one, for example:
Now after John was put in prison, Jesus came to Galilee, preaching the gospel of the kingdom of God, and saying, “The time is fulfilled, and the kingdom of God is at hand. Repent, and believe in the gospel.”
We interpreted that the same way you interpret a guy on the street corner with a sign that says, “The end is near.” In other words, “near” meant that it was still future, coming soon.
There’s an obvious way in which that was true. The consummation of the kingdom promises is still future. Obviously, the knowledge of the glory of God has not yet covered the earth like water covers the sea.
I’m aware that people have issues with the eschatology, but let’s not get sidetracked onto that at the moment. For the sake of discussion, let’s grant a future literal kingdom of exactly the kind envisioned by pre- and post-mil theologians.
Granting that, is the kingdom entirely future?
We know it isn’t, because it wasn’t entirely future even in Jesus’ day. Notice what He says in Matthew 12:
Every kingdom divided against itself is brought to desolation, and every city or house divided against itself will not stand. If Satan casts out Satan, he is divided against himself. How then will his kingdom stand? And if I cast out demons by Beelzebub, by whom do your sons cast them out? Therefore they shall be your judges. But if I cast out demons by the Spirit of God, surely the kingdom of God has come upon you.
“Has come.” Not “will come” or “is about to come.” Has. In other words, when Jesus cast out a demon, the kingdom came right there. And this is what Jesus meant all along when He said that the kingdom was near. The old King James translation, “The kingdom of heaven is at hand” is exactly right. “At hand” is where you keep your cell phone–close enough you can reach out and grab it.
The message of Jesus, from the inception of His ministry right down to the present day, is this: the kingdom of God is close enough to you, right now, that you could reach out and touch it. Do you want to?