The Kingdom in the Gospels
The phrase “kingdom of heaven” appears 32 in times in the Bible, all of them in Matthew! The phrase “kingdom of God” appears 52 times in gospels and after that an additional 14 times in the New Testament. “Kingdom” itself appears a whopping 126 times in the gospels, 17 times in Acts and Revelation combined, and an additional 18 times scattered through the rest of the New Testament. [All of the above are my own counts from an NASB concordance.]
My first reason for pointing these numbers out is to demonstrate that the Kingdom of God/Kingdom of Heaven is an important topic in the New Testament, and in fact the Bible as a whole. Indeed, some Christian teachers have proposed it as the unifying theme for all of Scripture. Certainly the kingdom of God makes a very rich topic for Biblical study, which I highly recommend.
More specifically I want to point out that, although the Kingdom of God theme is central to all of the NT and all of the Bible, the phrase itself is especially highlighted in the gospels (Matthew, Mark, and Luke in particular). There is good reason for that. The “Kingdom of God” is the same as the “Kingdom of Christ” (Col 1:13, II Tim 4:1, II Pet 1:11, Rev 11:15, Rev 12:10). And although this kingdom’s King is the focus of all of the Bible, it is in the gospels that the eternal Word becomes flesh, typology begins giving way to the typifier, and fulfillment of prophecy breaks forth as a flood.
So I would propose that it is not surprising that the more that Jesus is directly in view the more His kingdom would be directly in view. You see, the “kingdom of God” refers not so much to a realm as to a reign, not so much to a place as a the presence of God in providential, saving, benevolent kingship. (John Piper gives some clarifications in his sermon on Rom 14:16-19.) So even though God as Spirit is omnipresent and always reigning, still the physical presence of Jesus on earth, actively at work destroying the works of the evil one, and displaying His authority, means that the kingdom of Christ is “at hand” and “on the move” in a very special way.
Thus when we read the gospels we should come to them with eyes and ears prepared to see and hear what the kingdom of God is like in the life, love, ministry, teachings, and sacrifice of Christ. For example, most of Jesus’ parables are about what the kingdom of heaven is like. Eleven times (all of them in Matthew) Jesus explicity started out His parables saying, “The kingdom of heaven is like…”, but even many of the parables that don’t start that way are clearly displaying what the kingdom is like. The gospels are also an essential place to learn about who will or won’t enter into Jesus’ kingdom (Matt 5:20, Matt 7:21, Matt 18:3, John 3:5), and dangers to beware of for those who do long to to enter (Matt 19:23-24, Mark 9:47). Best of all, the gospels are an ideal place to “Behold your king” Himself!
P.S. The “gospel of the kingdom” is another great Biblical topic which, although related, is different from what I’m talking about here.