The kingdom of God is a present reality in our world accessible to those who will enter it through faith in Jesus. Those who participate in God's kingdom avail themselves to the power of God in this life. On this topic, Dallas Willard writes:

As a child I lived in an area of southern Missouri where electricity was available only in the form of lightning. We had more of that than we could use. But in my senior year of high school the REA (Rural Electrification Administration) extended its lines into the area where we lived, and electrical power became available to households and farms.

When those lines came by our farm, a very different way of living presented itself. Our relationships to fundamental aspects of life—daylight and dark, hot and cold, clean and dirty, work and leisure, preparing food and preserving it—could then be vastly changed for the better. But we still had to believe in the electricity and its arrangements, understand them, and take the practical steps involved in relying on it.

You may think the comparison rather crude, and in some respects it is. But it will help us to understand Jesus' basic message about the kingdom of heaven if we pause to reflect on those farmers who, in effect, heard the message: "Repent, for electricity is at hand." Repent, or turn from their kerosene lamps and lanterns, their iceboxes and cellars, their scrub-boards and rug beaters, their woman-powered sewing machines and their radio with dry-cell batteries.

The power that could make their lives far better was right there near them where, by making relatively simple arrangements, they could utilize it. Strangely, a few did not accept it. They did not enter the kingdom of electricity. Some just didn't want to change. Others could not afford it, or so they thought.

To be sure, that kingdom [God's] has been here as long as we humans have been here, and longer. But it has been available to us through simple confidence in Jesus, the Anointed, only from the time he became a public figure.