Although the Kingdom of God is not often talked about in churches today, it was the main topic of Jesus’ preaching. I believe that an understanding of the Kingdom is essential for Christians. Some people think the kingdom just doing good things now or heaven when we die or something Jesus will start when he returns.
One of the most influential scholars on this topic was George Eldon Ladd. I appreciate what he says in his A Theology of the New Testament.
Our central thesis is that the Kingdom of God is the redemptive reign of God dynamically active to establish his rule among human beings, and that this Kingdom, which will appear as an apocalyptic act at the end of the age, has already come into human history in the person and mission of Jesus to overcome evil, to deliver people from its power, and to bring them into the blessings of God’s reign. The Kingdom of God involves two great moments: fulfillment within history, and consummation at the end of history.