Heart

In biblical anthropology, the heart (lev or levav in Hebrew; kardia in Greek) is the central organ of the inner life — encompassing not merely emotion (as in modern usage) but the totality of a person's intellect, will, conscience, and moral character. The heart is the seat of understanding (1 Kings 3:9; Proverbs 14:33), of plans and intentions (Proverbs 16:9; Matthew 9:4), of faith (Romans 10:10), of worship (Deuteronomy 6:5), and of moral character (Matthew 5:8; 15:19). The great commandment calls for love of God with the whole heart (Deuteronomy 6:5; Matthew 22:37), establishing the heart as the organ of covenant relationship.

Scripture consistently presents the unregenerate heart as corrupt and self-deceived: "The heart is deceitful above all things, and desperately wicked; who can know it?" (Jeremiah 17:9). The prophets announced that the new covenant would involve a transformation of the heart itself — the law written on the heart rather than on stone tablets (Jeremiah 31:33; Ezekiel 36:26–27), replacing the "heart of stone" with a "heart of flesh" by the Spirit of God. The New Testament presents this as accomplished in regeneration: believers are sealed by the Spirit in their hearts (2 Corinthians 1:22; Ephesians 1:13–14), and the peace of God guards the heart (Philippians 4:7).