If you do not understand the problem, you will not seek the right cure. That is true not only medically but also spiritually. In Matthew 15 Jesus teaches a vital lesson in spiritual diagnosis. What He says is fundamental to living the Christian life. He exposes the superficiality of Pharisaical religion by putting His finger on the source of all our sinful behaviours. It is not what goes into a person that defiles him. It is what comes out of him — the corrupted streams that flow from a corrupted heart. “For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander. These are what defile a person. But to eat with unwashed hands does not defile anyone” (vv. 19–20). As has been well said, the heart of the human problem is the problem of the human heart. Not the blood pumping vessel that is the concern of your cardiologist, but the seat of your personality that is the concern of the Gospel.