In rebuking the religious leaders’ emphasis on man-made traditions instead of the Word of God, Jesus goes to the heart of the problem: our hearts. The heart of a person—that is, the core of who we are—is defiled by wickedness. Our hearts are corrupted by sin. It’s why Jeremiah pronounced our hearts “deceitful above all things and beyond cure” (17:9).
Theologian and Reformer John Calvin famously wrote, “Man’s nature, so to speak, is a perpetual factory of idols.” We set our hearts on always inventing new distractions and new things to adore instead of God.
Through Jesus Christ, there is a cure for our sinful hearts. When we repent and believe the gospel, God gives us a new, clean heart. But as long as we remain in this world, we are still sinners. James understood this. His words about harboring bitter envy and ambition in the heart, and about fights and quarrels coming from within, were written to believers (James 3:14; 4:1-2).
Trust Jesus fully. He changes everything—right down to your sin-tainted heart.