A Mortal Sin弥天大罪;罪大恶极
Not for any mortal sin不是因为罪大恶极
That is a mortal sin一种不可饶恕的大罪
N-VAR（有变体名词） In the Roman Catholic Church, a mortal sin is an extremely serious sin. Catholics believe the person who has committed it will be punished after death unless they are forgiven by the Church. (天主教的)不可饶恕的大罪