I will give you the keys of the kingdom of heaven; and whatever you bind on earth shall have been bound in heaven, and whatever you loose on earth shall have been loosed in heaven. Matt. 16:19, NASB.
Here we have another verse that has ripped through Christian history. Just what is it that Jesus promised Peter? What are the keys and the binding power of the church?
A key is an obvious metaphor for admitting people through a door. A hint to understanding the "key" symbol appears in Luke 11:52, in which Jesus condemns the scribes for misusing "the key of knowledge" and thereby hindering people from "entering" the kingdom. In Matthew 23:13 we find Him berating the scribes and Pharisees because they "shut the door of the kingdom of heaven in people's faces" and refuse to "let those enter who are trying to" (NIV). We should couple those verses with Jesus' saying in John 17:3 that to know Him is eternal life.
In their work, the scribes and Pharisees have been misusing the key and blocking people from knowledge of Jesus. Peter, by contrast, is to open the way. That is exactly what we find him doing in Acts 2 and 3, in which his preaching brings many Jews into the kingdom, and in Acts 10, in which he opens the door for Gentiles to enter. That role, of course, is not restricted to Peter. All true disciples proclaim the central key: that Jesus is the divine Christ. In Matthew 28:18-20 we find Him commanding all disciples to carry His message to the ends of the earth through the use of the teaching key so that many can come to a knowledge of Him and be baptized.
Peter's blessing also includes binding and loosing--a responsibility extended to all the disciples in Matthew 18:18. Most translations seem to infer that whatever the church decides on earth will get ratified in heaven. But that is not what Jesus said. The Greek verb tenses make it clear that the church on earth will carry out heaven's decisions, rather than heaven confirming the church's decisions.
With Matthew 16:16 and Peter's confession that Jesus is the divine Christ, we have come to a turning point in the gospel story. The disciples at last know who Jesus is, but not what that means. The what will provide the thread we need to follow as we turn our eyes upon Jesus as He moves toward the cross.