Nothing that enters a person from outside can defile him, but what comes out of him, that defiles the person.
Christ here reveals a pivotal truth in the whole conversation. He shows that the true source of moral and spiritual defilement is in the human heart. A person is not defiled simply by what enters into him from the outside, if the matter concerns a ritual diet or similar things. True defilement comes from what comes out of a person’s heart: words, deeds, and desires. This saying cuts off the entire false religious belief that it is possible to remain inwardly unchanged and at the same time be considered holy by outward rules. Christ brings a person back to his real problem: not the washing of hands, but the condition of the heart.