Matthew 15:18-19  "But what comes out of the mouth proceeds from the heart, and this defiles a person. For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander."

"I cannot imagine any condition which would cause a ship to founder. Modern shipbuilding has gone beyond that."

Titanic didn't sink because of visible; sank because of the hidden. 

Sins of the heart are more dangerous and destructive than what shows up in our actions. 
Sins of the Heart
1. LUST
Lust is an internalized sexual craving or arousal outside of marriage 
Matthew 5:28 "But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart."

Lust begins in the mind, not the moment of action
Lust objectifies and dehumanizes
Lust is never satisfied

2. BITTERNESS 
Hebrews 12:15 "See to it that no one fails to obtain the grace of God; that no 'root of bitterness' springs up and causes trouble, and by it many become defiled."
Matthew 18:35 (NIV)"This is how my heavenly Father will treat each of you unless you forgive your brother or sister from your heart
Corrie ten Boom: "Forgiveness is to set a prisoner free and discover that prisoner was you."
Anne Lamott: "Not forgiving is like drinking rat poison and then waiting for the rat to die."

3. ANGER
Matthew 5:21-22  "You have heard that it was said to those of old, 'You shall not murder; and whoever murders will be liable to judgment.' But I say to you that everyone who is angry with his brother will be liable to judgment..."


4. PRIDE
Mark 7:21-22 "For from within, out of the heart of man, come evil thoughts, sexual immorality, theft, murder, adultery, coveting, wickedness, deceit, sensuality, envy, slander, pride, foolishness."
Every sin flows from pride: "I know better than God," "I deserve this," "I'm entitled."

Revelation 3:17 (Laodicea) — "You say, I am rich, I have prospered, and I need nothing, not realizing that you are wretched, pitiable, poor, blind, and naked."
1 Peter 5:5 "God opposes the proud but gives grace to the humble."

5. Envy
Internal craving for what someone else has—possessions, lifestyle, kids, spouse, money.  
Luke 12:15 "Take care, and be on your guard against all covetousness, for one's life does not consist in the abundance of his possessions."
Hebrews 13:5 — "Keep your life free from love of money, and be content with what you have, for he has said, 'I will never leave you nor forsake you'"

"We can't steer around an iceberg you refuse to acknowledge."

Jesus invited us to a deep righteousness, not based on the letter of the law, but the heart.