What Makes a Sin "Mortal"? Understanding the Church's Teaching

Scripture itself draws a distinction between two categories of wrongdoing, referring to "sin which is mortal" and "sin which is not mortal" ( 1 John 5 : 16 − 17 ). The latter is what the Church calls venial or pardonable sin, which wounds our relationship with God but doesn't sever it. To understand what tips the scales and makes a sin mortal—or deadly—we must look to three essential criteria, as reiterated by St. John Paul II: the sin must be of grave matter, committed with full knowledge, and done with deliberate consent. These conditions are critical because they speak to the degree of harm to our soul and the deliberate nature of the choice. For instance, some acts, like murder, are considered intrinsically grave and mortal by their very nature. If we know an action is seriously wrong and freely choose it, we’ve effectively chosen that sin over God, a choice that radically changes our fundamental orientation away from Him. A common misconception that St. Jo...