Matthew 15:18Meaning & Commentary from the Church Fathers

He spoke to correct their misconceptions and, not satisfied with that, He elaborated further: What is consumed enters the stomach and is expelled, yet what emerges from the mouth is a reflection of the heart—this is what defiles a person. For from the heart arise wicked thoughts, murder, adultery, sexual immorality, theft, false testimony, and slander—these actions pollute an individual; however, eating with unclean hands does not contaminate a person (Mt. 15:17-20). Observe how forcefully He reproaches them. He reinforces His teachings with a universal truth of nature for their instruction. By stating, ‘It goes into the belly and is expelled,’ He addresses the concerns of the Jews.

Ideas originate within and stay there, yet when they manifest, that is, when they transform into actions and behaviors, they corrupt an individual.

Revere godliness as divine. Recognize the goodness of performing virtuous acts, and comprehend that harboring malicious thoughts is sinful; for even if you do not act upon your thoughts, the wickedness you conceive becomes etched in your spirit as if it were an image, while the likeness of goodness also remains imprinted within you. A righteous person embodies the thought of God, and the mind that seeks out hidden truths serves as a prophet for those in need. He who turns away from truth and seeks its shadow ultimately finds that refuge leads to his demise. Do not petition God for worldly riches that are fleeting, for the gifts from God are eternal.

Throughout the Gospel texts, heretics and the corrupted are beset with temptations. Some assert that the Lord, lacking knowledge of natural occurrences, believes that all nourishment simply goes to the stomach only to be expelled, despite the truth that food is absorbed and distributed throughout the body, reaching even to the marrow. Consequently, individuals suffering from gastrointestinal issues may frequently expel what they have ingested, yet still feel satisfied afterward, as liquid nourishment and beverages, upon first contact, permeate the body. However, interpreters of this sort demonstrate their own lack of understanding in their attempts to expose the ignorance of others. In actuality, even light liquids and foods, after being processed within the body’s systems, move to the lower regions and exit through the body's subtle openings, known in Greek as πόρους, and are subsequently eliminated in private.

In Matthew 12:34, it is stated that the mouth speaks from the overflow of the heart. Initially, a longing arises within the heart, which we subsequently articulate through our words. What is received from external sources is then voiced, while what emerges from our inner being can linger and lead to defilement.

You inquire about the origin of evil thoughts that arise from the heart and corrupt a person. The reason is that the watchful laborers, who are meant to remain alert and oversee the flourishing of the good seed, have become complacent. If we consistently maintained vigilance over ourselves, refraining from indulgence and slumber, and preserving the divine image within us, we would prevent the sowing of harmful seeds. Consequently, the enemy would not find an opportunity to take root in us and produce weeds destined for destruction.

Feet commit wrongdoing only if the soul desires it; hands act unacceptably only if the will permits it. The tongue utters hurtful words only if the heart consents. The body does not engage in immorality unless the heart chooses to do so. What value is there in refraining from external evil while harboring malevolence within? What merit is there in not stealing outwardly, yet internally being a thief? What good is it if one does not take a life with their hands, while internally fostering malice and thoughts of murder? The heart is where the murderer, the adulterer, and the thief reside. A container that is clean on the outside but filled with foulness within serves no purpose.

WHAT PROCEEDS FROM THE MOUTH OR FROM THE HEART - THESE ARE WHAT MAKE A PERSON IMPURE; for from the heart arise wicked intentions, including murder, adultery, theft, greed, deceit, slander, false testimony, blasphemy, complaint against God, arrogance, insanity, and countless other sins. All transgressions spring from sinful thoughts; these malevolent thoughts emerging from the heart contaminate an individual, even if he does not consciously affirm them; they nonetheless leave a mark on the spirit. When the heart temporarily entertains a sinful idea, the contamination of the soul is inevitable. Thus, wandering thoughts that linger in the soul already corrupt a person, and when acted upon, they not only taint him but also lead him to destruction. Evil thoughts within the heart are akin to burglars in a cave, always poised to emerge and manifest as wicked actions. The Savior concluded -

What, then, is the significance of the perplexing statement, "It shall not enter into the mouth"? Does it undermine Moses' laws regarding the distinction between clean and unclean foods, or not? If it does undermine these laws, how can it be reconciled with the regard for the law that led the Lord to dismiss the tradition of the Korban? If it does not undermine these laws, what understanding can we derive from it? The disciples were unsure how to interpret this, prompting them to seek clarification from the Lord. Peter requested that the Lord explain this parable to them. The Lord, taken aback by their lack of insight, emphasized that food, as an external entity, does not cause inner moral defilement. (This does not imply that all types of food are inconsequential to individuals.

After confronting the hypocrisy of the Pharisees, the Lord drew the people nearer and taught them about what is genuinely unclean, leading to their guilt before God. He instructed the crowd with a principle that what enters the mouth does not render a person impure, but what emerges from the mouth can defile a person. Following this declaration, as noted in Mark, Jesus entered a house where His disciples informed Him—an account unique to Matthew—that the Pharisees were offended by His teachings. The Apostles may have been troubled by the fact that Christ's words, which were meant to enlighten, appeared to instead lead the Pharisees into temptation.

"Do you lack understanding as well?” Christ asked. “Do you not see that nothing that enters a person from the outside can make him unclean?” (Mark 7:18). It doesn’t make him unclean, because it does not penetrate his heart but goes into his stomach and is eliminated, thus purifying all food (Mk. 7:19). What comes out of the mouth — from the heart — is what makes a person unclean; for from within, out of the human heart, arise evil thoughts, adultery, sexual immorality, murder, theft, greed, wickedness, deceit, shamelessness, envy, slander, pride, and foolishness — all these evils come from within and make a person unclean (Mk. 7:21-23). Eating with unwashed hands does not render a man unclean. There is no need to elaborate further on Christ's teachings; everything is evident.

The Savior instructed both the crowd and His disciples that within the kingdom of heaven, the purity of one’s heart holds greater significance than the cleanliness of one’s hands. "For out of the heart come evil thoughts, murders, adulteries, thefts, false testimonies, blasphemies." These actions truly "defile a person; but to eat with unwashed hands does not defile a person," and the rule regarding this stems merely from a common expectation of cleanliness, lacking any absolute moral weight as interpreted by the Pharisees, who are described as "blind guides of the blind."

The words that emerge from one’s mouth highlight a significant truth: even if food were to remain within the body, it would not render an individual impure. However, the impurity that resides within the heart is what truly corrupts a person; it does so not only while it remains there but also when it is expressed outwardly, intensifying the corruption (Zlat.). Similarly, the sinful desires that linger in the soul defile an individual and, when acted upon, lead not just to further defilement but ultimately to destruction (Theophilus). The heart serves as the core of the soul, from which good and evil deeds originate (cf. Matt. 22:37). In this discourse, the Lord focuses on the harmful thoughts and actions that arise from the heart, as the context necessitated addressing this particular aspect of human nature.

The disciples' inability to grasp the profound truths of the Kingdom of Heaven (Matt. 13:11) was worthy of admonition, prompting Jesus Christ to question them: "Are you also without understanding? Do you not realize that anything that enters a person from the outside cannot render them impure, since it does not reach their heart but rather goes into their stomach, and then exits the body, purging all impurities? But what comes out of the mouth is from the heart, and that is what defiles a person."