What is the Kingdom of Heaven?

The kingdom of heaven is neither a social nor economic order; it is an exclusively spiritual brotherhood of God-knowing individuals. True, such a brotherhood is in itself a new and amazing social phenomenon attended by astounding political and economic repercussions. ~ The Urantia Book, 99:3.2 (1088.3)

The kingdom of heaven is neither material nor merely intellectual; it is a spiritual relationship between God and man. ~ The Urantia Book, 134:4.2 (1486.5)

God is spirit, and God gives a fragment of his spirit self to dwell in the heart of man. Spiritually, all men are equal. The kingdom of heaven is free from castes, classes, social levels, and economic groups. You are all brethren. ~ The Urantia Book, 134:4.7 (1487.4)

The keys of the kingdom of heaven are: sincerity, more sincerity, and more sincerity. The highest moral choice is the choice of the highest possible value, and always—in any sphere, in all of them—this is to choose to do the will of God. ~ The Urantia Book, 39:4.14 (435.7)

“John came preaching repentance to prepare you for the kingdom; now have I come proclaiming faith, the gift of God, as the price of entrance into the kingdom of heaven. If you would but believe that my Father loves you with an infinite love, then you are in the kingdom of God.” ~ Jesus, The Urantia Book, 137:8.17 (1537.4)