Catechesis: Second Commandment

Now you understand what it means to take God’s name in vain. To repeat very briefly, it is either simply to lie and assert under His name something that is not so, or to curse, swear, conjure, and, in short, to practice wickedness of any kind. In addition you must also know how to use the name of God aright... for example, when we swear properly, where it is necessary and required. So, also when we teach properly; again, when we call on His name in time of need, or praise and thank Him in time of prosperity, etc.—LC I:62-64

*As an abuse of the divine name, consider these words of Pope Pius IX in promulgating the dogma of the immaculate conception of the Virgin Mary upon this very day in 1854: “We declare, pronounce, and define that the doctrine which holds that the most Blessed Virgin Mary, in the first instance of her conception, by a singular grace and privilege granted by Almighty God, in view of the merits of Jesus Christ, the Saviour of the human race, was preserved free from all stain of original sin, is a doctrine revealed by God and therefore to be believed firmly and constantly by all the faithful. Hence, if anyone shall dare -- which God forbid! -- to think otherwise than as has been defined by us, let him know and understand that he is condemned by his own judgment; that he has suffered shipwreck in the faith; that he has separated from the unity of the Church; and that, furthermore, by his own action he incurs the penalties established by law if he should dare to express in words or writing or by any other outward means the errors he thinks in his heart.”