What Constitutes Mortal Sin?



Dear Catholic Exchange,

I am a Catholic who visits your site very often for information. I have been doing research on mortal sin and I need clarification and was wondering if someone would be willing to help me with this. My question is this:

What constitutes mortal sin? Many articles make it sound like anything that is against the 10 commandments, including missing Mass on Sunday (with intention to miss). The passages I read in the Bible make it sound like a severe sin, which if left unrepented will lead to eternal death. I am having a very difficult time drawing the line between what is a severe unrepented sin in Scripture versus mortal sin. The term “grave sin” is used a lot and it confuses me even further! If there is someone I could have ongoing dialogue with on this issue, I would greatly appreciate it!

Thank you,

Diana Dages

Dear Ms. Dages,

Thank you for your questions regarding mortal sin and what constitutes a mortal sin. Please see our FAITH FACT on sin, which can be found at Persevering to the End: The Biblical Reality of Mortal Sin.

Addressing the issue of the use of the word “grave” to describe sin, it is used interchangeably with “mortal.” The Modern Catholic Dictionary by John A. Hardin, S.J. puts it this way:

The terms mortal, deadly, grave, and serious applied to sin are synonyms, each with a slightly different implication. Mortal and deadly focus on the effects in the sinner, namely deprivation of the stage of friendship with God; grave and serious refer to the importance of the matter in which a person offends God. But the Church never distinguishes among these terms as though they represented different kinds of sins.

I hope that this information is helpful. If you have further questions or comments please do not hesitate to call Information Services at 1-800-MY-FAITH. We offer this service to everyone entirely free of charge, and would appreciate any support, through prayers and donations, you could give us to help others.

United in the Faith,

Christopher Kreps

Information Specialist

Catholics United for the Faith

827 North Fourth Street

Steubenville, OH 43952

800-MY-FAITH (800-693-2484)



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