Shorter Catechism Q. 53. Which is the third commandment? A. The third commandment is, Thou shalt not take the name of the Lord thy God in vain: for the Lord will not hold him guiltless that taketh his name in vain. Q. 54. What is required in the third commandment? A. The third commandment requireth the holy and reverent use of God’s names, titles, attributes, ordinances, word and works.
Commentary: God identifies and reveals himself by his name(s). In the Old Testament, God gave the name “the LORD [Yahweh], the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob (Ex. 3:15).” He also proclaimed his name to be “The LORD, the LORD, a God merciful and gracious, slow to anger and abounding in steadfast love and faithfulness, keeping steadfast love for thousands, forgiving iniquity and transgression and sin, but who will by no means clear the guilty, visiting the iniquity of the fathers on the children and the children’s children, to the third and the fourth generation (Ex. 34:6-7).” In the New Testament, God reveals his name to be the Father, the Son and the Holy Spirit (Matt. 28:19). He also known as “the God and Father of our Lord Jesus Christ (Rom. 15:6).”
The third commandment forbids taking God’s name in vain, which means that we are not to misuse it (see NIV translation of Ex. 20:7). Consequently, this commandment requires “the holy and reverent use” of God’s names “in thought, meditation, word, and writing (WLC 112)”. But not just his names, also his “titles, attributes, ordinances, word and works” because God further reveals himself by these things.
God also gives his name to his people so that they are called by it (Num. 6:27; Deut. 28:10). Indeed, Christians are baptized into the name of the Triune God (Matt. 28:19). Since we bear God’s name, we use it reverently by living a godly life, or as the Larger Catechism says, “by an holy profession and answerable conversation [lifestyle], to the glory of God, and the good of ourselves and others (WLC 112).”