The biblical passage that makes reference to the “keys of the kingdom” is Matthew 16:19. Jesus had asked His disciples who people thought He was. After responding with several of the more popular opinions, Jesus aimed His question directly at His disciples. Peter, responding for the twelve, acknowledged Jesus as the Christ, the Son of the Living God. After this great confession, Jesus replied:
“Blessed are you, Simon Bar-Jonah! For flesh and blood has not revealed this to you, but my Father who is in heaven. And I tell you, you are Peter, and on this rock I will build my church, and the gates of hell shall not prevail against it. 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” (Matthew 16:17-19).
Keys are used to lock or unlock doors. The specific doors Jesus has in mind in this passage are the doors to the Kingdom of Heaven. Jesus is laying the foundation of His church (Ephesians 2:20). The disciples will be the leaders of this new institution called the church, and Jesus is giving them the authority to either grant or bar access to the Kingdom. The authority of the keys is to open and shut the doors to the Kingdom of Heaven. Precisely how do the keys to the kingdom work? Biblically speaking, how does one enter the Kingdom of Heaven?
Jesus tells us that unless one is born again, he will not see the Kingdom of Heaven (John 3:3). One is born again as the Holy Spirit works through the Word of God to bring about new life in dead sinners. So the faithful preaching of the gospel is one of the keys to the kingdom. The other key is church discipline. In Matthew 18:15-20, Jesus gives us the guidelines for church discipline. He specifically mentions in that passage the same “binding and loosing” language we find in Matthew 16. Similarly, in 1 Corinthians 5:1-13, Paul urges the Corinthian church to ex-communicate the man caught in adultery. Church discipline was considered by the Protestant Reformers as one of the marks of a true church (along with the preaching of the pure gospel and the administration of the sacraments).
Both of these keys—the preaching of the gospel and church discipline—function in opening and closing the doors to the Kingdom of Heaven. Through the preaching the gospel, those who respond in faith and repentance are allowed access to the Kingdom of Heaven; yet those who continue to harden their hearts and reject the gospel of God’s saving grace are shut out of the Kingdom. Similarly, through church discipline, the person who is caught in sin and remains unrepentant is barred access to the means of grace—the Word, the sacraments and fellowship with the community of believers. However, if the sinner repents, he or she can be allowed back into church and given access to all the means of grace therein.
So, the keys to the kingdom are the preaching of the gospel and the exercise of church discipline. When these are rightly administered, i.e., in a biblical church with duly appointed elders, access to the Kingdom of Heaven is ably guarded. However, when the keys are not used correctly through obscuring the message of the gospel or the lack of exercising church discipline, the results are disastrous. Consider Jesus’ warning to the Pharisees: “But woe to you, scribes and Pharisees, hypocrites! For you shut the kingdom of heaven in people’s faces. For you neither enter yourselves nor allow those who would enter to go in” (Matthew 23:13). If the gospel message is distorted or ignored, or if unrepentant sin is not adequately disciplined, the doors to the Kingdom of Heaven are being shut in people’s faces. When either of these two things occur, people in the church are either believing in a false gospel or they have not truly repented of their sin. In both cases the result is weeds growing in the wheat field of the church (Matthew 13:24-30).