HC 84

Heidelberg Catechism

Q84. How is the kingdom of heaven opened and closed by the preaching of the gospel?

According to the command of Christ, the kingdom of heaven is opened when it is proclaimed and publicly testified to each and every believer that God has really forgiven all their sins for the sake of Christ's merits, as often as they by true faith accept the promise of the gospel. The kingdom of heaven is closed when it is proclaimed and testified to all unbelievers and hypocrites that the wrath of God and eternal condemnation rest on them as long as they do not repent. According to this testimony of the gospel, God will judge both in this life and in the life to come.

Proof texts

Matt. 16:19 — [19] I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.”
John 3:31-36 — [31] He who comes from above is above all. He who is of the earth belongs to the earth and speaks in an earthly way. He who comes from heaven is above all. [32] He bears witness to what he has seen and heard, yet no one receives his testimony. [33] Whoever receives his testimony sets his seal to this, that God is true. [34] For he whom God has sent utters the words of God, for he gives the Spirit without measure. [35] The Father loves the Son and has given all things into his hand. [36] Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him.
John 20:21-23 — [21] Jesus said to them again, “Peace be with you. As the Father has sent me, even so I am sending you.” [22] And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit. [23] If you forgive the sins of any, they are forgiven them; if you withhold forgiveness from any, it is withheld.”

For discussion

The Assembly cited Matt. 16:19 in support of this answer. Read it in context — how does it bear on what is claimed here?
3 passages are cited here. Which does the most work, and is anything claimed that the proofs do not obviously carry?