Kidneys
The Kidneys in Israelite Sacrifice
The kidneys held a prominent place in Israel's sacrificial system. Because they are surrounded by some of the purest fat in the body, the kidneys and their fat were burned on the altar in every sacrifice where the entire animal was not consumed. This applied to peace offerings (Leviticus 3:4, 10, 15), sin offerings (Exodus 29:13; Leviticus 4:9; 9:10), and trespass offerings (Leviticus 7:4). The fat of the kidneys was considered especially sacred, as visceral fat was deemed the portion best suited for sacrificial burning. In Deuteronomy 32:14, "fat of the kidneys of wheat" is used as a proverbial expression for surpassing excellence. Isaiah 34:6 similarly uses "fat of the kidneys of rams" as a representative sacrificial term.
The Sacredness of Fat
The Israelites were strictly forbidden from eating the fat surrounding the internal organs, including the kidneys (Leviticus 7:22-25). This fat belonged to the Lord and was set apart for burning on the altar. The prohibition underscored the idea that the best portion of every sacrifice was to be given to God. When worshipers at the tabernacle or temple saw the kidney fat being burned, it was a visual reminder that God deserves the choicest and most excellent of what people possess (1 Samuel 2:16).
The Kidneys as a Symbol of the Inner Self
Because the kidneys are deeply hidden within the body and are among the last organs reached when an animal is cut open, they became a natural symbol for the most concealed part of a person. Psalm 139:13 uses the kidneys to represent the innermost being, declaring that God formed the psalmist's "inward parts" in the womb. In Job 16:13, having one's kidneys (reins) cleaved asunder represents total personal destruction.
The Seat of Conscience and Emotion
Beyond their physical hiddenness, the kidneys came to symbolize the seat of moral impulses and emotional life. The psalmist says his reins instruct him in the night (Psalm 16:7), and in Psalm 73:21 the pricking of the reins describes inner turmoil and conviction. Proverbs 23:16 speaks of the reins rejoicing when a person speaks what is right. Jeremiah notes that God is far from the reins of the wicked (Jeremiah 12:2), using the image to describe a conscience untouched by divine truth.
God as the One Who Searches the Kidneys
One of the most significant theological uses of kidneys in Scripture is the repeated declaration that God "tests" or "examines" the reins and the heart. This phrase appears in Psalm 7:9, Psalm 26:2, Jeremiah 11:20, Jeremiah 17:10, and Jeremiah 20:12. It expresses God's complete and penetrating knowledge of every human being's true character and motives. Revelation 2:23 carries this theme into the New Testament, where Jesus declares, "I am he who searches minds and hearts, and I will give to each of you according to your works." The kidneys thus serve as a reminder that nothing is hidden from God's sight.
Biblical Context
The kidneys appear throughout the Pentateuch in sacrificial regulations (Exodus 29:13; Leviticus 3-4, 7-9). They feature prominently in the Psalms and prophetic literature as symbols of the inner person (Psalm 7:9; 16:7; 26:2; 73:21; 139:13) and in Jeremiah as the object of God's searching gaze (Jeremiah 11:20; 17:10; 20:12). In the New Testament, Revelation 2:23 continues this figurative tradition.
Theological Significance
The kidneys illustrate the biblical principle that God sees beyond outward appearances to the hidden depths of the human heart. Their use in sacrifice teaches that the best and most intimate portions belong to God. Their figurative use as the seat of conscience affirms that moral awareness is not merely a human invention but a God-given faculty. The consistent pairing of 'reins and heart' in Scripture emphasizes that God's knowledge of each person is total and inescapable.
Historical Background
In the ancient Near East, internal organs were commonly believed to be the seat of emotions and thoughts. The Babylonians and Egyptians practiced divination by examining animal organs, especially the liver. Israel's sacrificial practices involving the kidneys and their fat parallel but also differ from these pagan customs, as the Israelite focus was on offering to God rather than on reading omens. The Hebrew word for kidneys, along with the Greek and Latin equivalents, reflects a widespread ancient understanding of the body's interior as morally and spiritually significant.