John Gill Bible Commentary

All these evil things come from within,.... All evil thoughts, words, and actions, take their rise from the inward parts of man; from his heart; which is sadly corrupted, and is the fountain from whence all these impure streams flow. And if these come from within, then not from without; they are not by imitation or are the mere effects of example in others: example may indeed, and often does, draw out the evil that is within; but it does not produce it there; if it was not there before, it could not draw it out from thence: and if all these evils come from within, then the inward part of man must be sinful and polluted, previous to the commission of these evil things; and from whence springs then that inward pollution? It is the fruit of original sin, of Adam's transgression; the consequence of which is, a corrupt nature, which is derived to all his posterity: for his nature being corrupted by sinning, and he having all human nature in him, the individuals of it could not be propagated by ordinary generation, without the pollution of sin cleaving to them; "who can bring a clean thing out of an unclean? not one", Job 14:4. Nor has there ever been any instance to the contrary, but the man Christ Jesus; whose human nature was holy, it not descending from Adam by ordinary generation; otherwise, all men, as David was, are "shapen in iniquity, and conceived in sin", Psa 51:5, and this is the source and spring of all sinful action, internal and external. And defile the man; both soul and body; all the powers and faculties of the soul, and all the members of the body; or "make a man common": these show him to be one of the common people, a very sinful man; as such were reckoned, and therefore are called emphatically, "sinners": and are joined with "publicans", who were esteemed the worst of sinners: from all which it appears, that sin in thought, word, and deed, is the defiling thing, and is what ought to be carefully avoided; and not meats, and the manner of eating them, provided moderation is used.