When Scripture calls God, or individual persons of the Godhead, “holy” (as it often does: Lev. 11:44-45; Josh. 24:19; Isa. 2:2; Ps. 99:9; Isa. 1:4; 6:3; 41:14, 16, 20; 57:15; Ezek. 39:7; Amos 4:2; John 17:11; Acts 5:3-4, 32; Rev. 15:4), the word signifies everything about God that sets him apart from us and makes him an object of awe, adoration, and dread to us. It covers all aspects of his transcendent greatness and moral perfection and thus is an attribute of all his attributes, pointing to the “Godness” of God at every point. Every facet of God’s nature and every aspect of his character may properly be spoken of as holy, just because it is his. The core of the concept, however, is God’s purity, which cannot tolerate any form of sin (Hab. 1:13) and thus calls sinners to constant self-abasement in his presence (Isa. 6:5).

Justice, which means doing in all circumstances things that are right, is one expression of God’s holiness. God displays his justice as legislator and judge, and also as promise-keeper and pardoner of sin. His moral law, requiring behavior that matches his own, is “holy, righteous and good” (Rom. 7:12). He judges justly, according to actual desert (Gen. 18:25; Pss. 7:11; 96:13; Acts 17:31). His “wrath,” that is, his active judicial hostility to sin, is wholly just in its manifestations (Rom. 2:5-16), and his particular “judgments” (retributive punishments) are glorious and praiseworthy (Rev. 16:5, 7; 19:1-4). Whenever God fulfills his covenant commitment by acting to save his people, it is a gesture of “righteousness,” that is, justice (Isa. 51:5-6; 56:1; 63:1; 1 John 1:9). When God justifies sinners through faith in Christ, he does so on the basis of justice done, that is, the punishment of our sins in the person of Christ our substitute; thus the form taken by his justifying mercy shows him to be utterly and totally just (Rom. 3:25-26), and our justification itself is shown to be judicially justified.

When John says that God is “light,” with no darkness in him at all, the image is affirming God’s holy purity, which makes fellowship between him and the willfully unholy impossible and requires the pursuit of holiness and righteousness of life to be a central concern for Christian people (1 John 1:5-2:1; 2 Cor. 6:14-7:1; Heb. 12:10-17). The summons to believers, regenerate and forgiven as they are, to practice a holiness that will match God’s own, and so please him, is constant in the New Testament, as indeed it was in the Old Testament (Deut. 30:1-10; Eph. 4:17-5:14; 1 Pet. 1:13-22). Because God is holy, God’s people must be holy too.