One of the most difficult concepts to teach is sin because everybody comes to it thinking they know full well what it is. For example, when I ask what some common sins are of the high school confirmands, the usual suspects include not doing homework, not doing chores, some will even talk about ~emotional chastity~ stuff. If these are our only recognized and understood sins (if they can even be called that), then we are in serious trouble. Wanna know the interesting thing? Over the past six years, in my experience, the confirmands most accepting of the teaching of sin and conscience formation and who are non-defensive of their own flawed selves tend to be openly atheist (forced to be there by their parents).