Mortal sin
WordNet
noun
(1) An unpardonable sin entailing a total loss of grace
"Theologians list seven mortal sins"
WiktionaryText
Noun
- In Roman Catholic theology, a mortal sin is a grave matter, such as murder or blasphemy, and is committed with the full knowledge and deliberate consent of the sinner. The committing of such a heinous sin causes a complete loss of grace and leads to eternal damnation unless absolved.