When you are teaching, you must adopt the same method. When you are explaining the Law, never, ever, add Gospel elements—except in conclusion. Even little children need to experience anguish and terror. The reason so many people assume that they are really good Christians is because their parents reared them to be miserable Pharisees. Their parents never made them aware of the fact that they are poor, miserable sinners. A person may have fallen into the most dreadful sins, but if he has been brought up properly, when he hears the Law preached, he will say to himself, “Sure enough, I am an awful sinner!” Yet the Pharisee has sunk even lower. It is much tougher to convert such Pharisees.
Law & Gospel: How to Read and Apply the Bible by C. F. W. Walther (A Reader’s Edition) p 93