“And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven: (Mt. 16:18-19).
In the above passage please note that Jesus uses “church” and “kingdom” interchangeably. In other words, the kingdom of God is the same as the Lord’s church. Here He promised to build His church and to give the “keys of the kingdom of heaven” to Peter which keys Peter used on Pentecost of Acts 2 to tell lost souls what they had to do in order to be saved and thus become a part of the kingdom – a part of the church.
Bob Winton writes on this passage, “Kingdom of heaven’ is used interchangeably with ‘my church’ of the preceding verse. These are simply two different descriptions of that special group of people who belong to Christ. “Church” describes their relationship to the world (they have been called out of the world); “kingdom” is a type of government (presided over by a king who has all authority), thus describes the method by which the Lord directs his people. The use of these terms interchangeably shows that the same organization is being described”
Many modern religious groups (the majority of Protestant groups) deny that the kingdom has been established. This denial rejects the plain implications of the text. That the kingdom of Christ and the church of Christ are identical is further demonstrated by the following:
1) Christ said that the Lord’s Supper would be eaten in the kingdom (Luke 22:29-30); but 1Corinthians 11:23-30 shows that it is eaten in the church (i.e., by the church); if the kingdom has not come, there is no authority for anyone to eat the Supper today.
2) Peter used the “keys” to “open” the church (Acts 2); but the keys pertained to the kingdom; therefore, the church and the kingdom are the same institution.”(Outlined Commentary on Matthew)
“If the kingdom has not yet been established, as many teach, then Peter lived the rest of his natural life and never got to use the keys at all. Why did Jesus give him useless keys?” (Allen Webster).
“The false idea of a yet future kingdom requiring a return of the Lord to establish it would also require a return of Peter, for to him were given the keys of the kingdom!” (Bobby Liddell)
The kingdom is here today – it is the same institution as the church of our Lord.