(83) Q. What are the keys of the kingdom?
A. The preaching of the holy gospel and Christian discipline toward repentance. Both of them open the kingdom of heaven to believers and close it to unbelievers.
(84) Q. How does preaching the holy gospel open and close the kingdom of heaven?
A. According to the command of Christ: The kingdom of heaven is opened by proclaiming and publicly declaring to all believers, each and every one, that, as often as they accept the gospel promise in true faith, God, because of Christ’s merit, truly forgives all their sins. The kingdom of heaven is closed, however, by proclaiming and publicly declaring to unbelievers and hypocrites that, as long as they do not repent, the wrath of God and eternal condemnation rest on them. God’s judgment, both in this life and in the life to come, is based on this gospel testimony.
(85) Q. How is the kingdom of heaven closed and opened by Christian discipline?
A. According to the command of Christ: Those who, though called Christians, profess unchristian teachings or live unchristian lives, and who, after repeated personal and loving admonitions, refuse to abandon their errors and evil ways, and who, after being reported to the church, that is, to those ordained by the church for that purpose, fail to respond also to the church’s admonitions—such persons the church excludes from the Christian community by withholding the sacraments from them, and God also excludes them from the kingdom of Christ. Such persons, when promising and demonstrating genuine reform, are received again as members of Christ and of his church.
Is the church merely a place where people receive teaching and enjoy fellowship? Or should the church also speak with authority about our eternal destiny?
Jesus has instructed the church to use heaven’s keys (Matt. 16:19). Keys lock and unlock, enabling and restricting access. We might buck at that picture of church authority. But it would be wiser to understand how Christ uses his keys in the church, and to personally use the church’s ministry to enter God’s kingdom.
What Are the Keys of the Kingdom?
God’s kingdom is his rule “established and acknowledged in the hearts of sinners by the powerful regenerating influence of the Holy Spirit.” To enter God’s kingdom is to come into a submissive and loving relationship with God. No one but Jesus, as the “royal heir of David” has “authority over entrance to the messianic kingdom.” Christ “has the key of David, who opens and no one will shut, and who shuts and no one opens” (Rev. 3:7). To his beloved people Christ says, “I have set before you an open door, which no one is able to shut” (Rev. 3:8). On the last day the enthroned Christ will welcome the sheep into his kingdom, and he will exclude the goats. But even in this age he begins to open the door to believers and close the door to unbelievers.
Prior to ascending, Christ told Peter—as one leader in his church—“I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven” (Matt 16:19; cf. John 20:22–23). Christ has not abdicated his reign but entrusted the stewards of his church with functional authority on earth (1 Cor. 4:1). The church merely declares God’s judgment. Christ will execute it. But as elders judge rightly, their decision reflects Christ’s decision. Put simply, ordained leaders use the keys to maintain meaningful church membership (Heb. 13:17). The church is “the most important visible embodiment of the forces of the kingdom.” How one responds to church preaching and discipline reveals their kingdom status.
What Is the Key of Gospel Preaching?
As a key locks and unlocks, true preaching discriminates between believers and unbelievers; it comforts the afflicted and afflicts the comfortable. God told Isaiah: “Tell the righteous that it shall be well with them.” But say, “Woe to the wicked! It shall be ill with him” (Isa. 3:10, 11).
Preaching opens the kingdom to believers.
Believers must not be left wondering if Christ is for or against them. Preaching turns the key of comfort when it helps believers rejoice in Christ and his saving work. John 3:16, with its word of promise and invitation to believe, illustrates how preaching opens the kingdom. Believers hear this kind of preaching and rejoice. “How sweet the name of Jesus sounds in a believer’s ear! It soothes our sorrows, heals our wounds, and drives away our fear.” The kingdom is opened as often as believers “accept the gospel promise in true faith.”
Preaching closes the kingdom to unbelievers.
John 3 also illustrates how preaching afflicts the comfortable: “He who does not believe is condemned” (John 3:18). John 3:18 is no less important than John 3:16. Preaching only the promises of the covenant and none of its curses “is one of the worst mistakes that a preacher can fall into.” Undiscriminating preaching “[s]tupefies the consciences and hardens the hearts of the ungodly, and ‘strengthens their hands, that they should not return from their evil way.’”
What Is the Key of Church Discipline?
Discipline sounds negative to us. And it acts in the reverse order of preaching—closing before opening. But the goal is positive.
Church discipline closes the kingdom to unbelievers.
Christ commands the church to discipline “those who, though called Christians, profess unchristian teachings or live unchristian lives.” The first steps are personal and gentle (Gal. 6:1). Genuine believers will normally be restored by the sincere admonitions of spiritual people. Otherwise church leaders must help show the danger of unrepentance. If a brother despises the church’s admonition, the “extreme remedy” must be used. Excommunication is exclusion not just from the local congregation but also from God’s kingdom. Excommunication delivers a person to Satan to wake him up to his disastrous situation that “his spirit may be saved in the day of the Lord” (1 Cor. 5:5). Church members should pray for and interact with those who have been excluded from the Christian community as they would with any unbeliever (Matt. 18:17). But they must resist giving the impression that their socializing is a sign of spiritual unity.
Church discipline opens the kingdom to believers.
The chief goal of discipline is “for the reclaiming and gaining of offending brethren.” The church must be poised to embrace repentant sinners with forgiveness and affirming love (2 Cor. 2:7–8). Church discipline has additional purposes: deterring others from similar sin, maintaining the reputation of Jesus and his gospel, and preventing God’s wrath. But if we forget to champion the goal of restoration, we will approach discipline with hearts that fail to reflect God’s preference for salvation over judgment.
In the keys of the kingdom the Lord gives the church a powerful tool. He names the disease of unrepentant unbelief. And he offers the cure: believe that “as often as [we] accept the gospel promise in true faith, God, because of Christ’s merit, truly forgives all [our] sins.”
 Louis Berkhof, Systematic Theology, 568.
 Dennis Johnson, Triumph of the Lamb: A Commentary on Revelation (Phillipsburg, NJ: P&R, 2001), 87.
 Zacharias Ursinus, Commentary, 446.
 Berkhof, Systematic Theology, 570.
 John Newton, Trinity Psalter Hymnal, 492.
 Thomas Scott, in Charles Bridges, The Christian Ministry (Carlisle, PA: Banner of Truth, 1959), 278.
 “Church Order of the United Reformed Churches in North America,” art. 56, https://www.urcna.org/church-order
 Westminster Confession of Faith, 30:3.