What is the heart of man according to the Bible?

The heart is often referred to in scripture as the seat of the affections and of the passions, also of wisdom and understanding — hence we read of 'the wise in heart,' also the Lord gave to Solomon 'a wise and understanding heart.' It is the centre of a man's being. But before the deluge God's verdict of man was that every imagination of the thoughts of his heart was only evil continually. Gen. 6:5. A similar verdict is found in Gen. 8:21, after Noah came out of the ark. And the Lord said, Out of the heart of man proceed evil thoughts and every form of wickedness. Mark 7:21. The law required man to love God with all his heart. The reception of the gospel must be in the heart, Rom. 10:9; and God enables a hearer to receive the good news in 'an honest and good heart,' upon which there is fruit. Luke 8:15. In new creation there is a 'pure heart,' the Christian being led by the Holy Spirit. 1 Tim. 1:5; 2 Tim. 2:22; 1 Peter 1:22.

In Scripture the heart is the centre of the thoughts, the affections and the will (Matt. 9:4; 12:34; 24:48), that is, the inner “switchboard” of man. This is why the writer of the Proverbs had already said, “Keep thy heart more than anything that is guarded; for out of it are the issues of life” (Prov. 4:23). This is an important warning!

In Scripture the heart is the centre of the thoughts, the affections and the will (Matthew 9:4; 12:34; 24:48), that is, the inner “switchboard” of man. This is why the writer of the Proverbs had already said, “Keep thy heart more than anything that is guarded; for out of it are the issues of life” (Proverbs 4:23). This is an important warning!

Scripture shows that there is an intimate connection between the two, and that the heart exercises a considerable influence over the mind. When the declension of man from the knowledge of God to the darkness and corruption of heathendom is described, it is first stated that they "became vain in their imaginations and their foolish heart was darkened." It then follows that "even as they did not like to retain God in their knowledge, God gave them over to a reprobate mind" (Rom. 1:21, 28). The heart foolish and darkened was the precursor of the reprobate mind. Again, the apostle prays for the Ephesians that God would give them "the spirit of wisdom and revelation in the knowledge of him; the eyes of your heart (not, "understanding" as in the A.V.) being enlightened: that ye may know what is the hope of his calling," etc. So that it is clear that while the knowledge of God was lost through the darkening of the heart, the full knowledge of Him is now communicated through the enlightening of the heart. Since the heart therefore is the highway to every true and proper apprehension of the things of God, it is of the highest importance that the heart should be strictly guarded; even as it is said, "Keep thy heart with all diligence, for out of it are the issues of life" (Prov. 4:23). So the apostle writes to the Philippians, "And the peace of God which passeth all understanding shall keep your hearts and minds through Christ Jesus" (Phil. 4:7), thus pointing out what alone can form an efficient garrison for the central citadel of man's nature.

For scripture uniformly teaches that the heart is the core of man's being. It is the seat of the affections and of the impulses that carry man forward in the path of life. The Lord Himself declared to those who were content to make clean the exterior of the platter that there is a fountain of uncleanness within, which they entirely ignored. It is from the heart that proceeds every thing that defileth (Matt. 15:19). The evil heart of the natural man therefore gives a colour to his every action; for it is thence the mischief springs (Matt. 5:28, 1 John 3:15). On the other hand, the heart of the renewed man is so to characterise every action that it may prove good and acceptable before God. As servants of Christ we are to do "the will of God from the heart" (Eph. 6:6). To this end the love of God has been "shed abroad in our hearts by the Holy Ghost which is given unto us" (Rom. 5:5). Indeed the very Spirit of God Himself is in our hearts to originate and characterise every affection. This the apostle teaches, "Because ye are sons, God hath sent forth the Spirit of His Son into your hearts, crying, Abba, Father" (Gal. 4:6; 2 Cor. 1:22).

This fact is of great moment to such as have learnt the deceitfulness of the natural heart (Jer. 17:9). We are not left to ourselves to produce proper feelings Godward. He Who gives us right thoughts of God and the Father gives us right feelings too. For He is the Spirit of love as well as of a sound mind (2 Tim. 1:7). It is He, Who fills the heart with such a sense of the incomparable love of God Rom. 5:5) that out of the abundance of the heart the mouth speaks (Matt. 12:34-35; Luke 6:45).

Man's moral centre is the heart. Out of it proceed seven streams of deadly evil, showing the inward moral pollution which the history of fallen man, from Cain downwards, has abundantly proved to be true.

121 As to the disciples, the Lord's answer goes much farther, while at the same time it makes evident the apostle's want of intelligence; in effect, the principle is evident. But what a picture of the heart of man followed, thanks be to God, by that of the heart of God and of His ways in grace! That which went out of the heart defiled the man. All is simple. But what is it that went out from it? Evil thoughts, murders, then a terrible list of those dark productions of a depraved and corrupt heart. But cannot the Lord relieve a little this gloomy picture by touches of light which are found in these hearts! He finds none. Thus characterised, He leaves the heart of man. He was not wanting in goodness, He knew the heart - knew everything about man; but beyond that list He is silent. It is not saying that there are not amiable features in the natural heart (that may be so even in animals), but morally this is what comes out of the heart, the fruits of the root of the sin which is there, restrained, kept in, modified, yet the fruit that man's heart produces wherever he is permitted to follow his inclinations.

262 But what are these poor hearts in their natural state? This is the second question the Lord takes up. He has already torn the veil of the hypocrisy by which the Pharisees and priests tried to conceal the impurity of their hearts, and to turn to their own account the external piety which they taught; the motives of their hearts are manifested, and the efforts which they make to cover the impurity and avarice of their heart appear; their hypocrisy is manifest. The Lord does not only rend the veil of hypocrisy, but discovers also that which the heart produces. This is what God does; He searches our hearts and manifests them, and then reveals His own. This is the uncovering not merely of the hearts of the Pharisees, but of the hearts of all men; that which goes out of the mouth defiles the man, because it proceeds from the heart. What a picture! The product of the human heart consists of malice, corruption, envy, … in a word, of nothing but vices.

In Matt. 15: we have two hearts revealed to us — the heart of man and the heart of God. In reply to the Pharisees' criticism of His disciples for eating with unwashed hands, our Lord laid down that a man is not defiled by that which goes into his mouth, but by that which comes out, the words being the expression of what is in the heart. He proceeded to draw an appalling picture of the human heart. According to His judgement, which cannot err, it is a pestilent sink of iniquity.

The Pharisees made clean the outside of the cup and platter, but that did not cleanse the inside, for it is that which comes from within defiles the man. The stream was bitter because the fountain was bitter; and the fruit was bad because the tree was bad. The fountain of a man’s defilement lies in his own heart. No attendance upon a religious ritual could be of any value. The mere fact of this only made men hypocrites. An appearance of sanctity and goodness might be, and had been, adopted by the Pharisees as an outward garb, leaving the seat of the disease untouched; but of what avail was that in the presence of One whose eye was upon the heart. And “out of it are the issues of life” (Prov. 4:23). There is nothing to be gained by attention to that which is merely external. If the tree were good the fruit would be good, and if the fountain were sweet the stream would be sweet; and if the heart were pure the man would be pure also. Not that which entereth into a man defiles him, but that which comes out. “Out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies: these are the things which defile a man.”

Though mingled with a great many hypocritical utterances, it is in the main true as regards man, that when he speaks he gives expression to that which he is, for out of the abundance of the heart the mouth speaks (Matt. 12:34). Hence we read, “Their throat is an open sepulchre; with their tongues they have used deceit; the poison of asps is under their lips: whose mouth is full of cursing and bitterness” (Rom. 3:13-14); all these things come out of the heart, the seat of life, “and they defile the man” (Matt. 15:18). These things manifest what he is, and they come forth out of the mouth.