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 each and every believer that, every time they believe the gospel promise, all their sins are truly forgiven 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