Signifies not so much the actual kingdom as the sway of the king
Kingdom of God (in Matthew, generally, KINGDOM OF HEAVEN).—In this expression the innermost teaching of the Old Testament is summed up, but it should be noted that the word kingdom means ruling as well; thus it signifies not so much the actual kingdom as the sway of the king—cf. the Chaldaic Hebrew: MLKVCH Dan., iv, 28-29. The Greek basileia of the New Testament also has these two meanings—cf. Aristotle, "Pol.", II, xi, 10; II, xiv; IV, xiii, 10. We find the teaching of the New Testament foreshadowed in the theocracy sketched in Ex., xix, 6; in the establishment of the kingdom, I Kings, viii, 7: "They have not rejected thee, but me, that I should not reign over them." Still more clearly is it indicated in the promise of the theocratic kingdom, II Kings, vii, 14-16. It is God Who rules in the theocratic king and Who will avenge any neglect on his part. All through the Psalter this same thought is found; cf. Ps. x, 5; xiii, 2; xxxi, 23; lxxxviii, 12, etc. In these passages it is constantly insisted that God's throne is in heaven and that there is His kingdom; this may explain St. Matthew's preference for the expression "kingdom of heaven", as being more familiar to the Hebrews for whom he wrote. The Prophets dwell on the thought that God is the Supreme King and that by Him alone all kings rule; cf. Isaias, xxxvii, 16, 20. And when the temporal monarchy has failed, this same thought of God's ultimate rule over His people is brought into clearer relief till it culminates m the grand prophecy of Dan., vii, 13 sq., to which the thoughts of Christ's hearers must have turned when they heard Him speak of His kingdom. In that vision the power of ruling over all the forces of evil as symbolized by the four beasts which are the four kingdoms is given to "one like the son of man". At the same time we catch a glimpse in the apocryphal Psalms of Solomon of the way in which, side by side with the truth, there grew up among the carnal-minded the idea of a temporal sovereignty of the Messias, an idea which was (Luke, xix, 11; Matt., xviii, 1; Acts, i, 6) to exercise so baneful an influence on subsequent generations; cf. especially Ps. Sol., xvii, 23-28, where God is besought to raise up the King, the Son of David, to crush the nations and purify Jerusalem, etc. In the Greek Book of Wisdom, however, we find the most perfect realization of what was truly implied by this "rule" of God—"She [Wisdom] led the just man through direct paths and chewed him the kingdom of God", i.e. in what that kingdom consisted.
In the New Testament the speedy advent of this kingdom is the one theme: "Do penance: for the kingdom of heaven is at hand", said the Baptist, and Christ's opening words to the people do but repeat that message. At every stage in His teaching the advent of this kingdom, its various aspects, its precise meaning, the way in which it is to be attained, form the staple of His discourses, so much so that His discourse is called "the gospel of the kingdom". And the various shades of meaning which the expression bears have to be studied. In the mouth of Christ the "kingdom" means not so much a goal to be attained or a place—though those meanings are by no means excluded; cf. Matt., v, 3; xi, 2, etc.—it is rather a tone of mind (Luke, xvii, 20-21), it stands for an influence which must permeate men's minds if they would be one with Him and attain to His ideals; cf. Luke, ix, 55. It is only by realizing these shades of meaning that we can do justice to the parables of the kingdom with their endless variety. At one time the "kingdom" means the sway of grace in men's hearts, e.g. in the parable of the seed growing secretly (Mark, iv, 26 sq.; of. Matt., xxi, 43); and thus, too, it is opposed to and explained by the opposite kingdom of the devil (Matt., iv, 8; xii, 25-26). At another time it is the goal at which we have to aim, e.g. Matt., iii, 3. Again it is a place where God is pictured as reigning (Mark, xiv, 25). In the second petition of the "Our Father"—"Thy kingdom come"—we are taught to pray as well for grace as for glory. As men grew to understand the Divinity of Christ they grew to see that the kingdom of God was also that of Christ—it was here that the faith of the good thief excelled: "Lord, remember me when thou shalt come into thy kingdom." So, too, as men realized that this kingdom stood for a certain tone of mind, and saw that this peculiar spirit was enshrined in the Church, they began to speak of the Church as "the kingdom of God"; cf. Col., i, 13; I Thess., ii, 12; Apoc., i, 6, 9; v, 10, etc. The kingdom was regarded as Christ's, and He presents it to the Father; cf. I Cor., xv, 23-28; II Tim., iv, 1. The kingdom of God means, then, the ruling of God in our hearts; it means those principles which separate us off from the kingdom of the world and the devil; it means the benign sway of grace; it means the Church as that Divine institution whereby we may make sure of attaining the spirit of Christ and so win that ultimate kingdom of God where He reigns without end in "the holy city, the New Jerusalem, coming down out of heaven from God" (Apoc., xxi, 2).