Heidelberg Catechism · 1563

Q10. Will God allow such disobedience and apostasy to go unpunished?

Certainly not. He is terribly displeased with our original sin as well as our actual sins. Therefore He will punish them by a just judgment both now and eternally, as He has declared: Cursed be every one who does not abide by all things written in the book of the law, and do them (Galatians 3:10).
Answer · Heidelberg Catechism

Scripture proofs

  1. [1]
    Exodus 34:7

    Keeping mercy for thousands, forgiving iniquity and transgression and sin, and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children’s children, unto the third and to the fourth generation.

    Psalms 5:4-6

    For thou art not a God that hath pleasure in wickedness: neither shall evil dwell with thee. The foolish shall not stand in thy sight: thou hatest all workers of iniquity. Thou shalt destroy them that speak leasing: the Lord will abhor the bloody and deceitful man.

    Psalms 7:10

    My defence is of God, which saveth the upright in heart.

    Nahum 1:2

    God is jealous, and the Lord revengeth; the Lord revengeth, and is furious; the Lord will take vengeance on his adversaries, and he reserveth wrath for his enemies.

    Romans 1:18

    For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness;

    Romans 5:12

    Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:

    Ephesians 5:6

    Let no man deceive you with vain words: for because of these things cometh the wrath of God upon the children of disobedience.

    Hebrews 9:27

    And as it is appointed unto men once to die, but after this the judgment:

  2. [2]
    Deuteronomy 27:26

    Cursed be he that confirmeth not all the words of this law to do them. And all the people shall say, Amen.

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