NOTES for Mar 7:14-23
The very fact that the disciples ask Him to explain what the Lord said to the people and the Pharisees about defilement is striking: "Nothing that enters a person from outside can defile him; but what comes out of him, that defiles a person." The point is that the understanding of sin as filth or dirt, common in many religions and also ordinary in the Old Testament, starts from the idea that the source of this dirt is outside the person. By coming into contact, bodily or morally, with this dirt that exists apart from you, you become soiled and unpleasant in God's eyes. The very vivid image of a stinking, unwashed person became permanently linked in human consciousness with the violation of God's design.
This idea of an external source of the evil that defiles a person is important because it greatly reduces the measure of our responsibility. Indeed, can we condemn a person who has stepped in a cow patty? We can only feel sorry for him. The option of laughing at him is, of course, not being considered. Yet the Lord says that the source of the evil that defiles a person is in the person's heart. Therefore we ourselves bear full responsibility for the evil that we, and only we, let into this world, and for the fact that God sees us in such a repulsive state.