There are always at least two levels to think through in the gospel narratives: the mind of Jesus of Nazareth and the mind of the author. Hopefully, you do not think their intents were too far apart, but it is worth thinking through.
- Jesus could have used any word, but he chose to say he was going to build his church. Regardless of what you think of church-Israel distinction, at least in Matthew 16 Jesus was conceiving of something future (I will build my church). So it is not that easy to just say the Church is the people of God from Genesis to Revelation.
- By the time Matthew wrote this, at least 30 years of church history has already occurred. The events of Acts 2, 4, 13, and so forth have already happened. Matthew’s readers would have a concept of “church” by the time they read what Jesus said. When they think of “church”, they think of loving community made up of those who are committed to advancing the kingdom of Christ. They already think of themselves as groups of people who are willing to die for the faith and are fighting to knock down the gates of hell. And now they read that Jesus said from the beginning that he was planning to use “the church” as his vehicle for kingdom advancement.
If we go with our working definition, it is not too difficult to hear Jesus saying “I tell you, you are Peter, and on this rock I will build my people as seen in the local assembly.”