The keys of the kingdom of heaven permit a person to enter it. Jesus gave Peter the keys, and then said to him, “…whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven” (See Mat 16:19). The concept of a key fits well with binding and loosing. For example, one who is bound in handcuffs can be loosed by the person with the keys. The one who holds the keys to the kingdom of heaven can permit people to enter or keep them locked out.
The keys of the kingdom are the truths concerning the kingdom of God especially the gospel of the kingdom. The good news or gospel of the kingdom is the truth that one may enter it through faith and repentance. It is the key by which the believer enters the kingdom of heaven, but also the key which keeps the door to the kingdom locked to the unbeliever.
Like Peter and the apostles before us, we hold the keys to the kingdom of heaven! Paul the apostle wrote, “But as we have been approved by God to be entrusted with the gospel, even so we speak, not as pleasing men, but God who tests our hearts” (1 Thessalonians 2:4). Though we are not apostles, we have been entrusted with the gospel of Christ. We must preach it so that people may believe and enter the kingdom of heaven.