And when he had called all the people unto him, he said unto them, Hearken unto me every one of you, and understand: There is nothing from without a man, that entering into him can defile him: but the things which come out of him, those are they that defile the man. … Do ye not perceive, that whatsoever thing from without entereth into the man, it cannot defile him; Because it entereth not into his heart, but into the belly, and goeth out into the draught, purging all meats? And he said, That which cometh out of the man, that defileth the man. For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, Thefts, covetousness, wickedness, deceit, lasciviousness, an evil eye, blasphemy, pride, foolishness: All these evil things come from within, and defile the man. (Mark 7:14-23)
The Lord Jesus Christ begins the text with an admonition to listen intently. He addresses the lesson to every individual and calls for understanding. With such earnestness by our Lord, we should pause and linger over His gracious Words. We should immediately comprehend that Christ is correcting a natural, common, and widespread misbelief among the religious.
What is this needed correction? It concerns that which actually makes a man unclean, dirtied, or defiled. The first lesson is that nothing external to a man, entering into him can make him unclean. Physical foods cannot make a man unclean. The physical enters and departs “physically.” In this, we must be careful. Paul admonished the Colossian church (2:20-21), wherefore if ye be dead with Christ from the rudiments of the world, why, as though living in the world, are ye subject to ordinances, (touch not; taste not; handle not; which all are to perish with the using;) after the commandments and doctrines of men? The movement from the things of Christ to mere external avoidances is an easy step for mankind.
The second lesson is that defilement does not enter a man from the outward but flows from the inward out. In other words, the ultimate source of defilement is within a man’s nature. Uncleanness, impurity, guiltiness, sin, and iniquity issue from our heart. Man’s nature is corrupt and perverse. The responses of our nature to things external are what defile us. Think though the issues that naturally flow out of one’s sinful nature: evil reasoning, following one's feelings, sensualities, hatreds, stealing, lusts, false witnesses, envies, wrong thoughts concerning God, boastings, foolishnesses, and such like. All these evil things come from within, and defile the man.
This is one of several reasons why a man or woman must be born again. There must be spiritual birth within of a divine nature; that is, the life of God. Self-will can only momentarily cage and deceitfully restrain the sinfulness of our heart. No man can change his nature. This must be an act of the Lord Jesus Christ. This is the gift of God by grace through faith.
Lastly, as believers, we must yield to the divine nature of Christ within us. Battle royal must be fought by the power of God through His Word. Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ (II Corinthians 10:5). We can fool others but God knows our heart. We are what we are inwardly. Even so every good tree bringeth forth good fruit (Matthew 7:17a).