The basis of the conflict here between Jesus and his critics (Pharisees and those who professionally know the Law) is the set of laws known as the 'laws of cleanliness'. Many of these laws came into being because of concerns for health: dirtiness could be a cause of harm for many in one's family or community, and it would often be better that one separate oneself from the public till one is no longer a physical threat to others' health. Given, however, that many of these practical health laws were tied in with the law of 'love of neighbor', they took on a religious meaning: not only were they the wisdom of men, but they were also the wisdom of God. Even when it became clear that some diseases (or uncleanness) no longer posed a threat to people as they once did many years or centuries ago, they were still to be obeyed because they had been understood to be the 'will of God'.
Jesus has reappraised the many laws of Israel. He understood that every law is valid to the degree that it expresses the one law of love of God and love of neighbor. Considering the laws about purification that the religious Jew thought he was obliged to obey, Jesus concluded that they had no force in that they did not offend God or neighbor. These traditional, but imperfect laws were in his view the 'laws of men'. If particular laws are to exist, they should reflect accurately the will of God that He be loved and that the neighbor be loved. All laws of the Church, then, are valid to the degree that they promote love of God and/or love of neighbor.
Needless to say, cleaning dishes, etc., did not affect love of God and love of neighbor, and so Jesus dispensed with this kind of law. He refused to claim that these laws express God's will. Others in Israel did not see things as Jesus did. Indeed, it is for this reason (and not for his miracles or personal, private life) that Jesus' death was desired and urged. It is crucial in life to know the will of God; to teach what is not the will of God merits a silencing which can include even death - or so it was in Jesus' time.
Jesus concentrates his preaching on repentance so as to enter the Kingdom of Heaven. It is what comes out of the heart that needs this repentance, and he will continue to concentrate on this and clear away what is not required of men and women to enter the Kingdom of God.
John Kilgallen, S.J.