What is the meaning of Mark 7:21?

For from within

Jesus points us away from mere externalism. “What comes out of a man is what defiles him” (Mark 7:20). Sin’s fountainhead is internal, not environmental.

• Jeremiah 17:9 calls the heart “deceitful above all things.”

• Matthew 15:18 repeats that what proceeds “from the mouth comes from the heart.”

• Romans 7:18 admits, “I know that nothing good lives in me.”

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the hearts of men

The “heart” is the control center of thought, will, and emotion. Every human heart, untouched by grace, is corrupted.

• Proverbs 4:23: “Guard your heart… for from it flow springs of life.”

• Ezekiel 36:26 promises a “new heart,” proving the old one is insufficient.

• Romans 10:10 shows that saving faith itself is rooted in the heart.

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evil thoughts

Sin germinates in the mind.

• Genesis 6:5—every intent of man’s heart was “continually evil.”

• James 1:14-15 shows desire conceiving sin.

• Philippians 4:8 directs believers to replace corrupt thoughts with what is true and pure.

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sexual immorality

Any sexual activity outside God-ordained marriage.

• 1 Corinthians 6:18: “Flee from sexual immorality.”

• Hebrews 13:4 honors the marriage bed.

• 1 Thessalonians 4:3-4 connects holiness to abstaining from such sin.

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theft

Stealing reveals distrust of God’s provision.

• Exodus 20:15: “You shall not steal.”

• Ephesians 4:28 tells the former thief to work and share.

• Malachi 3:8 rebukes Israel for “robbing” God.

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murder

Violent sin that begins with hatred.

• Exodus 20:13: “You shall not murder.”

• Matthew 5:21-22 equates anger with murder in seed form.

• 1 John 3:15 labels hate itself murderous.

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adultery

Breaking the marriage covenant through unfaithfulness.

• Exodus 20:14: “You shall not commit adultery.”

• Matthew 5:27-28 condemns lust as adultery of the heart.

• Proverbs 6:32 warns that the adulterer “destroys himself.”

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summary

Mark 7:21 exposes the real battlefield: the inner person. Evil thoughts, sexual sin, theft, murder, and adultery all sprout from an unredeemed heart. The law diagnoses; only Christ cleanses. When He reigns within, evil thoughts turn to godly meditation, immorality to purity, theft to generosity, murder to love, and adultery to covenant faithfulness.