Albert Barnes Commentary Matthew 16:19

"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." — Matthew 16:19 (ASV)

And I will give to you, etc. A key is an instrument for opening a door. The one who is in possession of it has the power of access, and has a general care and administration of a house. Hence, in the Bible, a key is used as a symbol of superintendence, an emblem of power and authority. See Isaiah 22:22; Revelation 1:18; Revelation 3:7.

The kingdom of heaven here means, doubtless, the church on earth . When he says, therefore, that he will give him the keys of the kingdom of heaven, he means that he will make him the instrument of opening the door of faith to the world—the first to preach the gospel to both Jews and Gentiles. This was done (Acts 2:14–36; Acts 10:1). The "power of the keys" was given to Peter alone solely for this reason; the power of "binding and loosing" on earth was given to the other apostles with him . The only preeminence, then, that Peter had, was the honour of first opening the doors of the gospel to the world.

Whatsoever you shall bind, etc. The phrase to bind and to loose was often used by the Jews. It meant to prohibit and to permit. To bind a thing was to forbid it; to loose it, to allow it to be done. Thus they said about gathering wood on the Sabbath day. "The school of Shammai binds it"—i.e., forbids it; "the school of Hillel looses it"—i.e., allows it.

When Jesus gave this power to the apostles, he meant that whatever they forbid in the church should have Divine authority; whatever they permitted, or commanded, should also have Divine authority—that is, should be bound or loosed in heaven, or meet the approval of God. They were to be guided infallibly in the organization of the church:

1. By the teaching of Christ, and
2. By the teaching of the Holy Spirit.

This does not refer to persons, but to things—"whatsoever," not whosoever. It refers to rites and ceremonies in the church. Such of the Jewish customs as they should forbid were to be forbidden; and such as they thought proper to permit were to be allowed. Such rites as they should appoint in the church were to have the force of divine authority. Accordingly, they forbade circumcision and the eating of things offered to idols, and strangled, and blood (Acts 15:20). They founded the church, and ordained its rites, as of divine authority.