Here is an excerpt from John Calvin’s sermon on Acts 5:13-16. He is commenting on the Luke’s reference to Jerusalem in Acts 5:16.

Let us consider that holy Scripture tells us that man’s salvation will be found only on Zion and in Jerusalem (Isaiah 37:32, 46:13, Joel 2:32). When the prophets tell us that if we want God to be our Savior, we must be counted among us people and come into his church. For the words “Jerusalem” and “Zion” signify the church of God. This is also the witness of our creed. What are we laying claim to when we say, “I believe in the church universal, the communion of saints, the forgiveness of sins?” In short, concerning eternal life, our Lord wanted to instruct us that if we want to attain his kingdom, we must first of all have our sins forgiven, which we could not have without being joined to a church. So when we are separated from it we are without forgiveness of sins and, consequently, eternal life. And yet, as I said, if we want God to be our Savior, we have to be in his church. For anyone who remains apart, it seems as though he were consciously depriving himself of the heavenly kingdom and had completely denounced his salvation. It is clear that if God has a company of believers, his majesty is in their midst. We have to join it and fit in. Otherwise, all our knowledge will serve only to condemn us.