What makes a mortal sin grievous

What makes a mortal sin grievous? For example if I lie to my mother with full intent of knowing what I was doing, would that make it a mortal sin? What if I was trying to cover something up that wasn’t serious or life threatening, would that make it a venial sin? I don’t always lie and this is just an example. Because people do things intentionally everyday that is sinful, but I don’t know what makes it grievous?

You should form your own conscious. It isn’t a good idea to post here to poll people who dont know you or your mind if you are culpable in sin. Dont lie, and honor your parents.

it was an example

For a sin to be mortal you need grave matter, full knowledge, and full consent. You can use the 10 commandments as a guide though it is not comprehensive. So lying to parents breaks 2 of the commands. You can discern if that is grave matter.

Great questions @DLedoux. I bet you would enjoy going to a class on the Catechism of the Catholic Church…you would meet many enjoyable people. This question would also be fun to ask a priest, just call or head to a parish nearby. Also check out saint Thomas Aquinas and find some good Dominican sites or check out Catholic Answers… I bet you will get all the info you need and then come back and let us know the answer. :slight_smile:. :grinning:

@DLedoux, in the example you gave of a lie, it is the content which determines the gravity (amongst other things). So if you were under legal age, living at home, and your mother asked you if you’d finished your homework and you told her yes (when knowing full well you hadn’t), then that would be a venial matter (finising the homework), and if your mother asked you if you went to school today and you said yes, when in fact you didn’t but went to the park with friends etc., then that would be graver than the unfinished homework.

As I understand it , whilst both are lies told to your mother, one is more serious than the other - unfinished homework versus wagging school for the day.

But I suggest you make an effort to form a friendship with your parish priest, then you will comfortable in asking him your questions, and he will be better placed to help you with any issues you have in coming to understand how to work out the gravity of any particular situation/sin.

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Thank you CRV! I have only gone to church a few times and I am still not allowed to take communion yet because I am not Catholic at the moment. I am gonna take classes soon so can’t wait! : )


You’re welcome DLedoux. You’ll learn a whole lot in RCIA classes and then you’ll be part of the family :grinning:

Take it slow during the classes, take notes of things you want to be further explained to you and don’t be afraid to ask questions! Who knows, maybe someone else in class has the same question but is too shy to ask!

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.” 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.

IOW, mortal sin has levels… but still mortal

We have a beautiful sacrament, reconciliation. If we spend effort trying to figure out whether a sin is venial vs mortal sin, … the answer is, go to reconciliation. Don’t try and think the system can be gamed. We’re all flawed people. And flawed people can and will find ways to excuse their behavior or reduce felonies to misdemeanors or no fault at all…right? I always say, go to confession. And be done with the sin .

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