The instruction of the kidneys

The instruction of the kidneys (the inward parts)

by Gerard Feller  vlag

God is the Creator of all things. God has created man in His image. The man (in Christ) is the representation God’s nature. Everything that is created by God has an important purpose, namely to glorify Himself (Rom.11:36). Having addressed the excellent analogies of the natural process of birth and the spiritual mysteries of the new birth in a previous edition of Promise (1), we now would like to focus on the ‘instruction of the kidneys (inward parts)’.


God says to Jeremiah (Jer.1:5): “Before I formed you in the womb I knew you,
And before you were born I consecrated you; I have appointed you a prophet to the nations”. David says: “O Lord, You have searched me and known me. For You formed my inward parts (kidneys); You wove me in my mother’s womb” (Psa. 139:1,13). All things came into being through Him, and apart from Him nothing came into being that has come into being. (Jn 1:3). By the means of the Word of God, we can discover spiritual truths in the starry sky and in the animal and vegetal world which He also has shown in the visible world. Or, as Paul describes it in the Epistle to the Romans (1:20): “For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made”. This also goes for the wonderful creation of the body and everything within the body.

We now want to address ‘the instruction’ of the kidneys (the inward parts). What is the meaning of the kidneys (the inward parts) in the body?Are we able to discover spiritual secrets and principles in these inward parts? It is fascinating to trace creation under the guidance of God’s Spirit, so that we can glorify Him.

The nature and functioning of the inward parts (2)

In order to recognize the spiritual secrets of the kidneys, it is necessary to tell something about the creation and effect of the kidneys. The kidneys are bean-shaped organs that are located above and against the backside of the abdomen. Each kidney is about 11 cm long, 6 cm wide and 4 cm thick. Together with the lungs and liver they take care of the homeostasis of the blood. Homeostasis is the capacity to regulate the balance of all functions of the body such as the temperature, the acidity, blood pressure and breathing. The kidneys are in control of the acid level in particular and the concentration of dissolved substances. They control the fluid and salt system and also produce hormones that have an impact on the increase of the blood pressure. Through the kidney artery 1500 liters of blood run daily through the kidney as a special filtration system. Each kidney consists of about a million nephrons or small filters.

Such a nephron is made up of 2 small tubes: an ascending and a descending tube. The length of the total tube system in both kidneys together is about 60 km! Out of the 1500 liters of blood, about 1.5 – 2 liters of urine is secreted daily.

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The urine contains waste substances such as urea and salts. A part of the concentration capacity of the kidney is based on a great number of semi-permeable tubes that variably absorb glucose, sodium and potassium ions and amino acids. This is partly an active process (sometimes selective) and partly a passive, osmotic process. The active part takes place in the cortex of the kidney while the passive part mainly takes place in the medulla. Furthermore, the concentration capacity of the kidneys is based on the parallel activity of the collecting ducts together with other tubes including the related blood vessels. Partly because of its anatomic construction, the kidney is suitable for the counter current principle. Because the blood vessels and kidney tubes are systems in which different solutions of different compositions are running side by side, it causes movements of the salts and water perpendicularly to the current direction of the blood and urine. In this way the blood will first be concentrated because the speed of the current is reducing, then it absorbs fluid from the first filtrate, absorbs salt from deep within the medulla and then it partly secretes it while ascending before it ultimately absorbs water again.

In the collecting ducts the urine descends again in the medulla, absorbs fluid, at least when the wall allows it, which depends on the necessary urine concentration. The whole process of the urine formation is mainly a passive process, especially due to the counter current principle. It requires no ‘metabolic energy’. These organs are in their structure and effect to be considered an ingenuous, astonishing, brilliant, life-saving filtering system, which has been well devised.

Some conceptions about the key word ‘kidneys’ in the Bible (from:3)

  • The kidneys are according to the Bible, very important because they are embedded in a layer of fat, which is of a great purity and quality, which makes the fat of the kidneys a proverbial term of an all surpassing excellence (Deu. 32:14) (4). Therefore the kidneys with the fat that is on them were burnt in every offering, whether it regarded thank offerings, sin offerings or guilt offerings (5).
  • Kidneys (in Hebrew כּליות - kelayoth (always in plural)) are according to the Hebrew psychology, the place of the deepest emotions and disorders of man which are known by God alone. The Hebrew word can also be translated into the heart (6).
  • The place of the kidneys in the body makes them very inaccessible and at the slaughtering of an animal they are the last organs that are reached.
  • Therefore they were a natural symbol for the most hidden part of a human (Ps. 139:13) and in Job 16:13 (splits my kidneys open) we see the effect of the total destruction of the individual (cf. Job 19:27); Lamentations 3: 13).
  • The hidden place and the use of the offerings were the source of the thought of a place for the most moral (and emotional) motives. That’s the reason why it is written: ‘the innermost being instructs’ (Psa. 16:7) or why the psalmist said ‘I felt stabbed in my kidneys’ (Psa. 73:21) and it can be said of God that He is far from the inmost being (Lexham English Bible) of sinners (Jer.12:2). Our word ‘conscience’ is an appropriate depiction. Therefore: ‘my inmost’ rejoices (Pro. 23: 16)… And: connected to the ‘heart’: God knows heart and kidneys (Psa. 7:10; 26:2; Jer.11:20; 17:10; 20:12).
  • God’s eyes see the deepest and most hidden place of man. God does not respond to the external and is not satisfied with the external side of what man shows. Man looks at the outward appearance, but God looks at the heart (1Sam.16:7b). That is revealing and soothing. Revealing, for He knows the most hidden parts of our hearts: everything that is evil and indecent (Psa.139:13), everything that evokes me to pride and rebellion against God (Psa.73:21). He tries and tests the hearts and mind (kidneys) (Psa.7:10)
  • Nothing is so unreliable and deceitful as the heart, it is desperately wicked, who can know it? It is me, the Lord Who searches the heart, Who tests the mind (kidneys), Who gives to each man according to his ways, Who gives to each man what he deserves (Jer.17: 9,10). The Bible speaks in this context of the searching by God about our inner man. “And do not enter into judgment with Your servant, For in Your sight no man living is righteous” (Psa. 143:2). Whoever comes into contact with the holy right of the Lord and learns to uphold it as to be worshipped must die. “I cried out: “Woe is me, for I am ruined! Because I am a man of unclean lips, And I live among a people of unclean lips” (Isa. 6:5). In addition to this: Whoever has learnt to know God in His holy right, surely will not and does not want to escape from it. He allows God to know and judge him. “Search me and try me, Lord and; know my heart (kidneys).
  • In Greek the word for kidneys is: νεφρὸς.it appears only in the New Testament, particularly in Revelation 2:23 “And all the churches shall know that I am He which searches the minds (kidneys) and hearts”. The church in Thyatira is being dealt with rigorously, for it allows the prophetess Jezebel to prophesy and to tempt God’s servants to fornicate and to eat offerings to idols. The exalted Lord cannot allow it to go unpunished. He will punish their descendants with the death penalty and all the churches will know that it is the Lord, Who examines heart and minds (kidneys).


The instruction of the kidneys (7)

If we are born again, the Holy Spirit will form our lives more and more according to the life of Christ (Rom.8:29). Therefore He uses our life (blood) by cleansing it and by giving it the right place (concentration capacity of the kidney) and in this way He gives us the right spiritual backgrounds and motives to form our thinking and acting. This is, as in the kidney, an awesome filtering process, in which hardships, consequences of sins, but also the suffering and the surrender of one’s own life (blood) is used as a counter current principle to guide the born again man further into the knowledge and wisdom of God (Phil. 2:10; Heb. 2: 17,18). Due to the filtration process, this wisdom which is from God and free from all horizontal hindrances (counter current), is working in a wonderful way. It is partly a passive process; the Holy Spirit works it out in us, which is to be compared with the passive osmosis in the kidney, which is the major and most important part and is combined with our active work out of the will which the Holy Spirit works in us. This is comparable to the active process in the kidneys which is selective and takes energy: the selective part of the reabsorption of the kidney. In Phil 2:12b-13 it is briefly summarized as follows: “So then, my beloved, just as you have always obeyed (read: obeyed My will), not as in my presence only, but now much more in my absence work out your salvation with deep reverence toward God”. Or even clearer in another translation: “Work out your salvation with fear and trembling, for it is God who works in you to will and to act in order to fulfil his good purpose”.

Knowledge from the instruction of the kidneys (inward parts)

In this way our blood (life) is being filtered and the Holy Spirit gets to work and as we can read in Ephesians 1:17-19, Paul prays for the Ephesians: “That the God of our Lord Jesus Christ, the Father of glory, may give to you a spirit of wisdom and of revelation in the knowledge of Him.  I pray that the eyes of your heart may be enlightened, so that you will know what is the hope of His calling, what the riches are of the glory of His inheritance in the saints, and what the surpassing greatness is of His power toward us who believe. These are in accordance with the working of the strength of His might”. This “knowledge of Him’ must be rooted in love. It is the knowledge in the sense of having fellowship, which is a knowledge that cannot be used for boasting. Intellectual knowledge alone does not make a person to be more humble or loving. The knowledge that does not boast, is a knowledge that comes forth from the knowledge in the sight of Christ (2Cor.4:6). We must be alert that we do not gain knowledge that goes beyond our conscience (and our kidneys) (8). No, the instruction of the kidneys is the knowledge that is acquired through the fellowship with God. Only when you love God, you are known by Him (1Cor. 8:1-2).

The knowledge such as some Corinthians had, made them arrogant, empty. Real knowledge is in love and truth: ‘eating from the tree of life’. We gain real knowledge when we present our whole body and everything that is in it, as a sacrifice acceptable to God (Rom. 12:1; 2) (compare it with the meaning of the kidneys as an offering in the Old Testament!) (5). The way we receive instruction of the kidneys is when we listen to and are obedient to His Word, for then we gain a right spiritual discernment or: a right discernment of spirits. It is a learning process in God’s school. Real knowledge, as it has been said earlier, does not go beyond the conscience. The conscience has after all been purified by the blood (life) of Christ. Therefore our love must abound still more and more in real knowledge and all discernment, so that we may approve the things that are excellent (Phil. 1:9, 10).

That happens through the spiritual filtration process which we can compare to the functioning of the kidneys. The blood must not become too acid or contain too little salt or sugar; the blood pressure must be right, the quality of the blood must be optimal and the waste substances must be secreted. That is what Christ wants in our lives, namely that our actions and walk happen from a deeply inward fellowship with Him. Spiritually, metaphorically, the kidneys represent the inward man: his deepest feelings and affections. Therefore God examines our inward parts (Psa.7:4) and David says in Psa. 26: “Vindicate me, O Lord, for I have walked in my integrity, And I have trusted in the Lord without wavering. Examine me, O Lord, and try me; Test my mind and my heart”. The instruction of the kidneys adds a lot of value to us. Proverbs 23:15, 16: “My son, if your heart is wise, My own heart also will be glad; And my inmost being will rejoice”. Spurgeon wrote (8): ‘The wise man sees more with his eyes closed at night than the fool can see with his eyes open at daytime’. We conclude this instruction of the kidneys with Psa. 16:7-9a: “I will bless the Lord who has counseled me; Indeed my mind (kidneys) instructs me in the night. I have set the Lord continually before me; Because He is at my right hand, I will not be shaken.  Therefore my heart is glad and my glory rejoices; My flesh also will dwell securely”.

Gerard Feller, march 2018

Translated by Ursula Moestapa


  • Promise Magazine, april 2013.
  • L. Bouman, Compendium Fysiologie.
  • Wilhelm Gesenius hebräisches und aramäisches Handwörterbuch über das Alte Testament. 16e 1915 en Abr. Trommius, Nederlandse concordantie (6e herz. dr.).
  • Keil en Delitzsch schrijven bij Deut.32:14 (het vette der tarwe): “Kidney-fat (i.e., the best fat) of wheat,” the finest and most nutritious wheat.Job 16:13; Klaagl. 3:13 (nieren in het menselijk lichaam). Vanwege het ingewandenvet was dit deel van het dier het meest gepast voor vuuroffers en werd daarom in het bijzonder heilig geacht (Lev. 7:22-25; 1 Sam. 2:16).
  • dank- (Lev. 3:4, 10, 15; Lev. 9:19), zond- (Ex. 29:13; Lev. 4:9; 8:16; 9:10), of schuldoffers (Lev. 7:4); ‘de ram der vuloffers’ (wijdingsoffer) (Ex.29:22; Lev. 8:25). Daarom is in Jes. 34:6 het vet van de ‘nieren van rammen’ (= het beste van de rammen) gekozen als een typerende offerterm, parallel aan ‘bloed van lammen en geiten.’
  • Job 19:27; Ps. 7:10; 16:7; 26:2; 73:21; Spr. 23:16; Jer. 11:20; 12:3; 17:10; 20:12.
  • Gerard Feller, Het onderwijs van de nieren. Promise Magazine 2e jaargang nr. 2.
  • Ouweneel, Wijzen weten beter. Uitg. Pieters Groede. ISBN 90.6085.135.8!Facebook!Google!Live!Yahoo!

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