Lord's Day 31

Q. 83.  What are the keys of the kingdom of heaven?1
A.  The preaching of the holy gospel, and Christian discipline,2 or excommunication out of the Christian church;3 by these two, the kingdom of heaven is opened to believers, and shut against unbelievers.

Q. 84.  How is the kingdom of heaven opened and shut by the preaching of the holy gospel?
A.  Thus: when according to the command of Christ4 it is declared and publicly testified to all and every believer, that, whenever they receive the promise of the gospel by a true faith, all their sins are really forgiven them of God, for the sake of Christ’s merits;5 and on the contrary, when it is declared and testified to all unbelievers, and such as do not sincerely repent, that they stand exposed to the wrath of God and eternal condemnation, so long as they are unconverted;6 according to which testimony of the gospel God will judge them, both in this and in the life to come.

Q. 85.  How is the kingdom of heaven shut and opened by Christian discipline?
A.  Thus: when according to the command of Christ,7 those who under the name of Christians maintain doctrines, or practices inconsistent therewith,8 and will not, after having been often brotherly admonished, renounce their errors and wicked course of life, are complained of to the church,9 or to those who are thereunto appointed by the church;10 and if they despise their admonition, are by them forbidden the use of the sacraments;11 whereby they are excluded from the Christian church, and by God Himself from the kingdom of Christ; and when they promise and show real amendment, are again received as members of Christ and His church.12