What are the three conditions for a mortal sin?

• A. Grave matter only
• B. Full knowledge only
• C. Grave matter, full knowledge, and complete consent
• D. Free will without knowledge

Answer: (C)

For a mortal sin to happen, three things must be true at the same time: the act is grave matter (a very serious wrong), you have full knowledge that it’s wrong, and you freely choose to do it with your own will. If any one of these isn’t present, it isn’t a mortal sin—it might be a venial sin or nothing at all. For example, knowing something is wrong and freely choosing it, and the act itself is very serious, would be mortal. If you don’t realize the act is wrong, or the act isn’t very serious, or you’re not freely choosing it (perhaps you’re pressured), then it doesn’t meet all three conditions. So the three conditions are grave matter, full knowledge, and complete consent.