Somebody told me that driving fast is a mortal sin. I can’t believe that. Is it?
Yes, if it threatens harm to you or anyone else. The Catechism of the Catholic Church says: “The virtue of temperance disposes us to avoid every kind of excess: the abuse of food, alcohol, tobacco, or medicine. Those incur grave guilt who, by drunkenness or love of speed, endanger their own and others’ safety on the road, at sea, or in the air” (CCC 2290).