What is a "Serious Matter"

[BornInMarch]

One of the requirements for a sin to be mortal (i.e. for it to be bad enough to keep you out of Heaven) is that it be a Serious Matter.

Only what is a serious matter? I’ve heard people say that seemingly trivial things were mortal sins, and that has made it difficult to take it with the severity it warrants. Is there a standard definition of grave matter, or is it one of those situations where you can’t define it but you know it when you see it?

 

[Vico]

One of the requirements for a sin to be mortal (i.e. for it to be bad enough to keep you out of Heaven) is that it be a Serious Matter.

Only what is a serious matter? I’ve heard people say that seemingly trivial things were mortal sins, and that has made it difficult to take it with the severity it warrants. Is there a standard definition of grave matter, or is it one of those situations where you can’t define it but you know it when you see it?

Catechism

1858 Grave matter is specified by the Ten Commandments, corresponding to the answer of Jesus to the rich young man: "Do not kill, Do not commit adultery, Do not steal, Do not bear false witness, Do not defraud, Honor your father and your mother."132 The gravity of sins is more or less great: murder is graver than theft. One must also take into account who is wronged: violence against parents is in itself graver than violence against a stranger.

Also see Cateshism

2390 The sexual act must take place exclusively within marriage. Outside of marriage it always constitutes a grave sin.
2384 Divorce is a grave offense against the natural law.
2383 The separation of spouses while maintaining the marriage bond can be legitimate in certain cases provided for by canon law.
2352 …masturbation is an intrinsically and gravely disordered action.

Modern Catholic Dictionary

GRIEVOUS MATTER. Moral obligations that are binding under pain of mortal sin. The gravity of the matter is determined by the object and circumstance of the action (or omission) and is known in the first place by the teaching authority of the Church, based on divine revelation. Some sins do not admit of slight matter, and these are mortal sins “from their whole nature” (ex toto genere suo), as lust and blasphemy. In other sins the matter is not always grave, as in theft or injustice, and these are mortal “from their nature” (ex genere suo). In every case, however, for a mortal sin there is also required full advertence of the mind to the fact that the matter is serious, and full consent of the will to do or not do what a person knows is a grave command or prohibition.