Vice and Sin

A sin is a human act (that is, a deliberate thought,word, deed, desire, omission) contrary to right reason, and therefore contrary to God. A vice is a habit of sin. Vice is a morally bad habit; it stands contrasted with virtue which is a morally good habit. And sin, which is a vicious act, is contrasted with a virtuous act, that is, a morally good act.

Vice is contrary to order and reason; it is opposed tothe rational nature of man.

In itself, a bad act is worse than a bad habit; for abad act is a deed done, whereas a bad habit is only a stabledisposition to commit bad deeds. Even human law punishes a criminal act, but not a criminal disposition.

One sin does not destroy the opposed virtue as a habit. Just as one good act does not establish a virtue, so neither does one bad act establish a vice. But one mortal sin destroys all infused virtues as virtues (as living and active virtues), but notas habits. A mortal sin destroys charity and thus renders faith and hope inoperative for getting a man on towards heaven. Mortal sinrobs faith and hope of their power as virtues, but it does not expel them as habits. Venial sin neither destroys nor expelscharity or other virtues.

A person who sins by omission must, of course, be doing something at the time, but, for the sin of omission no determinateact is required to take the place of the omitted duty. The sin of omission is not in what a person is doing but in what he is failing to do.

Sin is sometimes defined as “word, deed, or desire contrary to the eternal law.” The definition is adequate, for sinful “words, deeds, desires,” involve thoughts andimaginings. And a sin of omission is actually a deed; it is the deed of omitting what one should do.