Q84. How does preaching the gospel open and close the kingdom of heaven?

According to the command of Christ: The kingdom of heaven is opened by proclaiming and publicly declaring to all and every believer, each time they believe the gospel promise, that all their sins are really forgiven them by God, for the sake of Christ's merits. The kingdom of heaven is closed by proclaiming and publicly declaring to unbelievers and hypocrites that, as long as they do not repent, the wrath of God and eternal condemnation rest on them.1