Lexicon

G2588 - kardia

Strong's: G2588 · BLB lookup Pronunciation: kar-dee'-ah Part of speech: feminine noun LXX equivalent: renders Hebrew lev / levav (heart, H3820, H3824) NT occurrences: 156

Semantic range

In biblical anthropology, kardia (heart) is the integrated center of the inner person, encompassing:

Intellect / understanding, the seat of thought (Romans 1:21, "their foolish kardia was darkened")
Volition / will, the seat of decision (Acts 11:23, "with purpose of kardia")
Emotion / affection, the seat of feeling (John 14:1, "do not let your kardia be troubled")
Moral / spiritual orientation, the deepest core of the person before God (Mt 5:8, "blessed are the pure in kardia")
Memory (Lk 2:19, Mary "treasured all these things in her kardia")
Conscience in some contexts (overlaps with G4893 - syneidesis)

Modern Western thought has split these functions across multiple categories (head / heart / will / emotion). Biblical thought integrates them all in the kardia / lev.

Theological force

The heart is the deepest level of the person

Scripture consistently presents the kardia as where the real person resides:

1 Samuel 16:7, "man looks at the outward appearance, but the LORD looks at the kardian"
Proverbs 4:23, "watch over your kardian with all diligence, for from it flow the springs of life"
Matthew 15:18-19, "the things that proceed out of the mouth come from the kardias… for out of the kardias come evil thoughts, murders, adulteries, fornications, thefts, false witness, slanders"
Mark 7:21-23, the moral source of evil is the kardia

The pattern: outward behavior reflects the inner kardia. Hypocrisy is precisely the disconnection of outward action from inner kardia.

Salvation as a heart-transformation

NT salvation language consistently focuses on the kardia:

Romans 10:9-10, "if you confess… and believe in your kardia… for with the kardia a person believes, resulting in righteousness"
2 Corinthians 1:22; 4:6; 5:5, God's Spirit poured into the kardia
Galatians 4:6, "God has sent forth the Spirit of His Son into our kardias"
Ephesians 1:18; 3:17, Christ dwells in the kardia through faith
Hebrews 10:22, "let us draw near with a sincere kardia in full assurance of faith"
2 Peter 1:19, "the day dawns and the morning star arises in your kardiais"

The NT pattern: regeneration produces a new kardia; sanctification deepens / purifies the kardia; eschatologically the believer's kardia will be perfectly conformed to Christ.

The OT promise, new heart

Ezekiel 36:26-27, "I will give you a new kardian and put a new spirit (pneuma) within you; and I will remove the kardian of stone from your flesh and give you a kardian of flesh. I will put My Spirit within you."

Jeremiah 31:33, the New Covenant promise: "I will put My law within them and on their kardian I will write it."

These OT promises are fulfilled in NT regeneration. The Christian's heart-transformation is the realization of OT eschatological promise.

Kardia and the head / mind

The biblical kardia is not contrasted with mind (as modern Western thought often does, "follow your heart vs your head"). The biblical kardia includes the mind. Romans 10:9-10 has kardia believing, i.e., the heart is the believing-thinking-trusting organ.

The modern Western "head vs heart" split is actually a post-Romantic conceptual development. The biblical anthropology is more integrated: kardia = the whole inner self, including thought.

Notable verses

Cardiac purity

Matthew 5:8, "blessed are the pure in kardia, for they shall see God"
1 Timothy 1:5, "love from a pure kardia"
2 Timothy 2:22, "those who call on the Lord from a pure kardia"

Cardiac hardening / unbelief

Mark 6:52; 8:17, disciples' kardia hardened
Romans 1:21, Gentile kardia darkened
Romans 2:5, sklērotēs kardias, hardness of heart
Hebrews 3:8, 12, 15; 4:7, "do not harden your kardian"

Cardiac transformation

Romans 5:5, "the love of God has been poured out within our kardiais through the Holy Spirit"
Romans 10:9-10, believe in your kardia
Ephesians 3:17, "Christ may dwell in your kardiais through faith"
Hebrews 10:22, sincere kardia
2 Peter 1:19, morning star arises in your kardiais

The heart and discipleship

Mark 12:30 / Mt 22:37, love God with all your kardias
Luke 6:45, "the good man out of the good treasure of his kardias"
John 14:1, "do not let your kardia be troubled"

Patristic / scholarly note

Patristic engagement:

Augustine (Confessions, extensive cor / kardia engagement; the famous "our kardia is restless until it rests in Thee")
The desert tradition (Evagrius, Cassian), heart-centered prayer / monasticism
Eastern Orthodox hesychasm, "prayer of the heart"

Modern conservative engagement:

Wayne Grudem (Systematic Theology) on biblical anthropology
John Piper (Desiring God; emphasis on heart-affections)
Jonathan Edwards (Religious Affections, 1746), the foundational Reformed treatment of heart-religion
Tim Keller, heart-idolatry diagnostic in pastoral application

Notes

Lexical workspace for kardia.