Heidelberg Catechism · Lord's Day 31
84. How is the kingdom of heaven opened and shut by the preaching of the gospel?
Answer
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 accept this promise of the gospel by true faith. The kingdom of heaven is shut when it is proclaimed and publicly testified to all unbelievers and hypocrites that the wrath of God and eternal condemnation rest upon 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.
Scripture references
Matthew 16:19 · John 3:31-36 · John 20:21-23
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