What is the difference between the Kingdom and the Church?
Every believer will be in the Kingdom, but not every believer will be in the Church. To enter the Kingdom new birth is essential (John 3: 3-5); to be in the Church requires the permanent indwelling of the Holy Spirit as well. The Kingdom and the Church can be thought of as two concentric circles: the inner circle is the Church and the outer one is the Kingdom. Hence all who are in the Church will be in the Kingdom, but the converse is not true, namely that not all those within the outer circle of the Kingdom are in the Church. Abraham will be in the Kingdom (Matt. 8: 11), but not in the Church.
Unlike the Kingdom, the Church was never the subject of OT prophecy; rather it was the subject of NT revelation, firstly by the Lord and then in its peculiar character as the body of Christ through Paul. Contrasting what is said about each in Scripture may help clarify the difference between the two.
The Kingdom is said to be “set up” (Dan. 2: 44, Acts 15: 16); the Church is “built up” (Col. 2: 7, see also Eph. 2: 20-22, 1 Cor. 3: 9). We read of “heirs of the kingdom” (James 2: 5), and of “sons of the kingdom” (Matt. 8: 12), but not of the Church. We read of seeing the Kingdom (John 3: 3); of receiving it (Luke 19: 12, 15); of inheriting it (Matt. 25: 34); and of entering it (Matt. 18: 3). We never find such expressions used of the Church. (In Acts 2: 47 the Church is added to rather than entered.) In the Kingdom national identities are retained (Matt. 25: 31-46); in the Church they are lost (Gal. 3: 28). Those of the Church are chosen before “[the] world’s foundation (Eph. 1: 4); but the Kingdom was only prepared from “[the] world’s foundation” (Matt. 25: 34). Many figures are used of the Church. It is described as a house (1Tim. 3: 15), a temple (1 Cor. 3: 16, 17), and a body (1 Cor. 12: 27), but never as a kingdom. Christ is the Head over all things to His body, the Church (Eph. 1: 22, 4: 15, Col. 1: 18), but He is never called its King. Of the parables in the Gospels, many are parables of the Kingdom, but there are no parables of the Church. [The similitude of the kingdom in Matt. 13: 45 is distinctly said to be of the merchant, not the pearl].
If the Kingdom is not the Church, how are they linked? When the King’s herald, John the Baptist appeared, he proclaimed to Israel, and to no one else, that the “kingdom of the heavens has drawn nigh” (Matt. 3: 2). When John was imprisoned the Lord continued this proclamation with exactly the same words (Matt. 4: 12, 17) and later sent out the twelve with the same message, instructing them to go only to “the lost sheep of the house of Israel” (Matt. 10: 5-7). Only when the King was refused on earth did He veil His ministry in parables and speak about the mysteries of the Kingdom: instead of the Kingdom being set up publicly, the King would retire to heaven, Peter would be given the keys (Matt. 16: 19), and when the King was enthroned above, Peter would use those keys to allow not only the Jew (Acts 2), but later the Gentile (Acts 10), to enter by baptism in submitting to the authority of the King in heaven. Baptism, having nothing to do with the Church, is always the means of outward entrance into the Kingdom. Hence in the Kingdom at present there is wheat and darnel, real (born again and baptised) and unreal (just baptised). At the “completion of [the] age”, (not the rapture), when the King returns in glory, the two will be separated and “the righteous” will enter the Kingdom in the millennium (Matt. 13: 37-43). During the forty days of resurrection, the Lord spoke, not of the Church, but of the Kingdom (Acts 1: 3). Hence on His departure, the disciples ask, not about the Church, but about the restoration of the Kingdom to Israel (Acts 1: 6). Throughout the Acts, which is transitional in character, although the Church is here, the teaching is not of the Church, but of the Kingdom, and even at the end (Acts 28: 31), we read of Paul “preaching the kingdom of God, and teaching the things concerning the Lord Jesus Christ, with all freedom unhinderedly”. If the Jew had repented, the King would have returned and publicly established the Kingdom (Acts 3: 19-21) for he was standing ready to return (Acts 7: 56).
When the Kingdom is imminent the glad tidings that are preached are the “glad tidings of the kingdom”. This was so when the King was here (Matt. 4: 23), and will be so again at the end of the age, when the Church has gone, just before the King returns in glory (Matt. 24: 14). The last we hear of the glad tidings of the kingdom is in the intermediate state of things in Acts 8: 12. When the King in heaven was refused by Israel (Acts 7: 54-60), Paul was taken up as the minister of the glad tidings (Col. 1: 23), and of the Church (Col. 1: 24, 25), and the glad tidings are “of the grace of God” (Acts 20: 24), which Paul speaks of in Rom. 16: 25 as “my glad tidings”.
When the Lord announced that Peter would be given the keys of the Kingdom, He also announced the building of His Church (Matt. 16: 13-20). Both these announcements came as a result of Peter’s confession that “Thou art the Christ, the Son of the living God.” The Kingdom is linked with the former; the Church with the latter. As the Christ (the anointed) He is King; as the Son of God He is the rock on which the Church is built. Immediately after this revelation, the disciples are to no longer announce Him as the Christ on earth (Matt. 16: 20). At Pentecost, the Church is in existence before Peter uses any of the kingdom keys and in his preaching he never ever announces Jesus as the Son of God but always as the Christ. His testimony is that Jesus has been made “both Lord and Christ” (Acts 2: 36). His testimony is to the resurrection proving that He is Christ and so in Acts 5: 42 we read that they were “announcing the glad tidings that Jesus [was] the Christ”. However, immediately after the rejection of Stephen’s testimony to the Son of Man standing in heaven (ready to return and establish the Kingdom) - Acts 7, Paul is called. However, his immediate testimony is not to Jesus as the Christ, but “that he is the Son of God” (Acts 9: 20). Once the rejection of the Lord as the anointed King, the Christ, the Messiah, was complete, then the glad tidings of the Kingdom are put in abeyance, the glad tidings become those of the grace of God, and the Church becomes the vessel of testimony, rather than Israel. Peter, whose ministry is in relation to the Kingdom, is overshadowed by Paul whose ministry is in relation to the Church. Peter was taken up by the Lord for the Kingdom; Paul for the Church and thus Paul alone is recorded as speaking of the Church in its unique character as the body of Christ. When the Church has been raptured, the vessel of testimony will then largely be the remnant in Israel testifying to the imminence of the Kingdom just prior to the King’s return to establish that Kingdom in power and glory.