A mortal sin, in Catholic theology, is a gravely sinful act, which can lead to damnation if a person does not repent of the sin before death. A sin is considered to be “mortal” when its quality is such that it leads to a separation of that person from God’s saving grace. Three conditions must together be met for a sin to be mortal: “Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent.”
在天主教神学中，Mortal Sin指的是一种罪孽深重的行为，如果一个人在死前不作忏悔，可能会被罚下地狱。当罪的性质足以导致该人与上帝的救恩分离时，就被认为是“罪孽深重”。定性为罪孽深重，必须同时满足三个条件：“不郝之罪是指在完全知晓后果且故意实施的情况下所犯下的严重罪行（致人丧命、令受害者及其家庭蒙受巨大的身心摧残等）。”
The sin against the Holy Ghost and the sins that cry to Heaven for vengeance are considered especially serious. This type of sin is distinguished from a venial sin that simply leads to a weakening of a person’s relationship with God. Despite its gravity, a person can repent of having committed a mortal sin. Such repentance is the primary requisite for forgiveness and absolution.
违背圣灵，或者是被人哭诉向天伸冤的罪恶被认定为罪孽深重，这种罪行与那些轻微的过失（venial sin）不可同日而语，轻罪带来的后果只是与上帝关系的疏远。而罪孽深重者要想获得上帝的宽恕和赦免，向上帝忏悔其罪行是首要前提。
