Heidelberg Catechism · 1563

Q85. How is the kingdom of heaven closed and opened by church discipline?

According to the command of Christ, people who call themselves Christians but show themselves to be unchristian in doctrine or life are first repeatedly admonished in a brotherly manner. If they do not give up their errors or wickedness, they are reported to the church, that is, to the elders. If they do not heed also their admonitions, they are forbidden the use of the sacraments, and they are excluded by the elders from the Christian congregation, and by God Himself from the kingdom of Christ. They are again received as members of Christ and of the church when they promise and show real amendment.
Answer · Heidelberg Catechism

Scripture proofs

  1. [1]
    Matthew 18:15-20

    Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican. …

    1 Corinthians 5:3-5

    For I verily, as absent in body, but present in spirit, have judged already, as though I were present, concerning him that hath so done this deed, In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ, To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.

    1 Corinthians 5:11-13

    But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat. For what have I to do to judge them also that are without? do not ye judge them that are within? But them that are without God judgeth. Therefore put away from among yourselves that wicked person.

    2 Thessalonians 3:14-15

    And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed. Yet count him not as an enemy, but admonish him as a brother.

  2. [2]
    Luke 15:20-24

    And he arose, and came to his father. But when he was yet a great way off, his father saw him, and had compassion, and ran, and fell on his neck, and kissed him. And the son said unto him, Father, I have sinned against heaven, and in thy sight, and am no more worthy to be called thy son. But the father said to his servants, Bring forth the best robe, and put it on him; and put a ring on his hand, and shoes on his feet: …

    2 Corinthians 2:6-11

    Sufficient to such a man is this punishment, which was inflicted of many. So that contrariwise ye ought rather to forgive him, and comfort him, lest perhaps such a one should be swallowed up with overmuch sorrow. Wherefore I beseech you that ye would confirm your love toward him. …

Proof texts as given in the original; verse text from the King James Version.