Definition of mortal sin
: a sin (as murder) that is deliberately committed and is of such serious consequence according to Thomist theology that it deprives the soul of sanctifying grace — compare venial sin 1
First Known Use of mortal sin
MORTAL SIN Defined for English Language Learners
Definition of mortal sin for English Language Learners
in the Roman Catholic Church : a sin (such as murder) that will result in punishment that lasts forever unless the person who has sinned sincerely confesses to God and asks to be forgiven
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