In the New Testament, the meaning of “heart” in Greek is captured by the word kardia. While we use this word today in a strictly medical sense (like “cardiology”), the biblical writers used it to describe the internal life of a human being. The kardia is the “inner sanctum” of a person—the place where your thoughts, passions, desires, and even your logic intersect to form who you truly are.
The Physical Center and the Spiritual Core
The Greeks, much like the Hebrews before them, used physical organs to describe spiritual realities. Just as the physical heart is the center of blood circulation and physical life, the kardia is the center of spiritual life. It is the core of the human personality. When the Bible speaks of the heart, it isn’t talking about a muscle; it’s talking about the “real you” that exists beneath the surface of your outward appearance.
Because the kardia is the center of our being, it is also the place where God does his most important work. We can fake our outward behavior, but we cannot fake our hearts before God. He looks past our words and our actions to see the true motives hidden in the kardia. Understanding this Greek term helps us realize that Christianity isn’t a program of behavioral modification, but a total heart transformation.
The Seat of Thinking and Feeling
In modern Western culture, we often separate the “head” (reason) from the “heart” (emotion). We say things like, “I know it in my head, but I don’t feel it in my heart.” However, the Greek word kardia merges these two concepts. In the New Testament, the heart is where we process information, doubt, believe, and reason. It is the place where our intellectual convictions meet our deepest feelings.
Romans 10:10 For it is by believing in your heart that you are made right with God, and it is by openly declaring your faith that you are saved.
Notice that Paul doesn’t say we believe with our “brains,” but with our hearts. This suggests that true biblical faith is more than just agreeing with a set of facts. It is a deep-seated conviction that takes hold of our entire inner person. When we understand the meaning of “heart” in Greek, we see that God wants to engage our minds and our emotions together in a unified pursuit of him.
The Battlefield of the Will
The kardia is also described as the seat of the will. It is the place where we make our final decisions and commitments. Every choice we make is birthed in the heart before it is ever carried out by our hands. This makes the heart a spiritual battlefield. It is where we decide whether to follow our own selfish desires or to submit to the leading of the Holy Spirit.
Jesus frequently pointed out that the condition of the heart determines the quality of a person’s life. He taught that a “good man brings good things out of the good stored up in his heart” (Luke 6:45). If the heart is cluttered with bitterness, pride, or lust, those things will eventually leak out into our lives. But if the heart is surrendered to Christ, it becomes a wellspring of love, joy, and peace that flows outward to everyone we meet.
Jesus Dwelling in the Heart
The most beautiful aspect of the kardia is that it is the intended home for Jesus Christ. The New Testament authors emphasize that through faith, Christ actually takes up residence in our inner selves. This isn’t just a metaphor for thinking about Jesus; it is a spiritual reality. When the Spirit of God dwells in our hearts, he begins to reshape our desires and clarify our thinking from the inside out.
Ephesians 3:17 Then Christ will make his home in your hearts as you trust in him. May your roots go down deep into God’s love and keep you strong.
This indwelling presence of Christ is what makes spiritual growth possible. We don’t have to struggle to be “better people” by our own willpower. Instead, we allow the “Master of the House” to rearrange the furniture of our lives. As Christ makes his home in our kardia, our hearts become more like his—full of compassion, truth, and unwavering devotion to the Father.
The Takeaway
The meaning of “heart” in Greek reveals that our kardia is the central hub of our existence. It is the place where our thoughts, emotions, and choices converge. God is not interested in mere religious performance; he wants access to this inner control center. When we invite Jesus to dwell in our hearts, he transforms our entire identity, aligning our deepest desires with his kingdom and his will.
