The second commandment prohibit the use of God 's name in vain . Many ancient cultures believed that names was sacred ; some had prohibitions on when a person 's name could be spoken . The Gospel of John relate an incident where a group of Jews attempted to stone Jesus after he used a sacred name of God to refer to himself . They interpreted his statement as a claim of divinity . Since they did not believe that he was God , they considered this blasphemy , which under Mosaic law carry a death penalty . Kreeft write that all of the names by which God is known are holy , and thus all of those names are protected by the second commandment . The Catechism state , " Respect for his name is an expression of the respect owed to the mystery of God himself and to the whole sacred reality it evoke . " The Catechism also require respect for the names of people out of respect for the dignity of that person .