From that time Jesus began to preach, saying, "Repent, for the kingdom of heaven is at hand." (Matthew 4:17)The first word recorded for us in Matthew from the lips of our Saviour is a command: Repent! From this single command, we have enough information to— once and for all— dispense of the idea that Jesus is a tolerant man who merely meets you where you're at and doesn't demand that you live a holy life.
This command for repentance was nothing new. The prophets of old had always called for it. In fact, Jesus' first words in Matthew, "Repent, for the kingdom of heaven is at hand," are identical to John the Baptist's first recorded words, "Repent, for the kingdom of heaven is at hand" (Matthew 3:2).
Anything repeated twice should certainly draw our attention. This message of repentance is central to the Gospel. Any preacher who removes the command to repent from sin in his proclamation of God's kingdom cannot be called a Christian preacher at all; such a preacher has neglected to mention the first words out of both John the Baptist's and our Savior's mouths!
But what are we to make of that phrase: "the kingdom of heaven"? Is this kingdom already here, or is it yet to come?
Throughout his gospel, Matthew often refers to the "kingdom of heaven". The phrase is unique to Matthew. Mark and Luke instead use the phrase "kingdom of God". The two phrases are identical in meaning (for instance, compare Mark 1:15 to Matthew 4:17).
When Jesus was on earth, He proclaimed that "the kingdom of God is in the midst of you" (Luke 17:21). He also said that "if it is by the Spirit of God that I cast out demons, then the kingdom of God has come upon you" (Matthew 12:28). Paul writes that God has delivered Christians "from the domain of darkness and transferred us to the kingdom of his beloved Son" (Colossians 1:13). We see, then, that God's kingdom is, in one sense, already here— and Christians are its citizens.
Yet other passages make it clear that God's kingdom is something we have not yet entered. Jesus said, "Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven..." (Matthew 7:21). Our entrance into the "eternal kingdom of our Lord and Saviour Jesus Christ" (1 Peter 1:11) is something that will happen in the future.
From this, we conclude that the kingdom of heaven has already come, but it is not yet here in its fullness. Not until the end of the age, once Satan has been conquered, will the kingdom of heaven be seen in its fullness. For now, we must be content to ask the same question that the disciples asked shortly before Jesus' ascension, "Lord, will you at this time restore the kingdom to Israel?" (Acts 1:6).
We can be assured that one day, the kingdom will be here in its fullness. We will see it, and we will live in it. For now, we look forward in expectation of that day when the seventh angel will blow his trumpet and proclaim, "The kingdom of the world has become the kingdom of our Lord and of his Christ, and he shall reign forever and ever" (Revelation 11:15).