We are quick to blame circumstances, people, or environments for our sin, just as the Pharisees did with their man-made traditions. They assumed defilement came from something outside of them—food touched by Gentiles, unwashed hands, unclean environments. But Jesus confronts this thinking head-on: the real problem is not out there, but inside of us. “There is nothing outside a person that by going into him can defile him, but the things that come out of a person are what defile him” (v. 15). External things may tempt or pressure us, but they cannot make us unclean. Defilement is not transferred from the outside in; it flows from the inside out.
When Jesus explained this to His disciples, He clarified that food enters the stomach, not the heart. The heart—our center of thought, will, and desire—is the real issue. Outward religion may scrub the “outside of the pot,” but unless the inside is cleansed, it remains corrupt. This is why Scripture warns repeatedly about the heart: “Every intention of the thoughts of man’s heart was only evil continually” (Gen. 6:5); “The heart is deceitful above all things and desperately sick” (Jer. 17:9). Jesus’ teaching here echoes the prophets—our deepest problem is not environment or circumstance but our own sinful hearts.
From within, Jesus says, flow “evil thoughts, sexual immorality, theft, murder, adultery, coveting, wickedness, deceit, sensuality, envy, slander, pride, foolishness” (vv. 21–22). This catalogue of sins mirrors the second half of the Ten Commandments, showing how inner corruption spills out into outward violation of God’s law. Notice that it begins with evil thoughts and ends with foolishness—what fills the heart gives rise to the mind, which then gives birth to action. Whether it is sexual immorality (porneia, encompassing any sexual activity outside of marriage between one man and one woman), hatred that Jesus equates with murder, or coveting that Paul calls idolatry—each comes from within. As Spurgeon said, “Sin is not a splash of mud upon man’s exterior; it is a filth generated within himself.”
If the problem lies in us, then the solution must come from outside of us. The world insists the answer is to look within and stay true to ourselves. But Jesus teaches the opposite: we are the problem, and only He can cleanse us. The Holy God took on flesh in Jesus Christ, who lived without sin, bore our guilt on the cross, and rose victorious. And to all who call on Him by faith, He gives a new heart with new desires, washing and sanctifying us by His Spirit (1 Cor. 6:11). This is why we cannot simply blame others, minimize our sin, or settle for outward religion. Our hope is Christ alone, who not only forgives but indwells us to fight sin and pray with David, “Create in me a clean heart, O God, and renew a right spirit within me.”
Main Idea – If the problem is primarily in us, the solution must be outside of us.