There is a profound teaching in Matthew 15:1ff about the "teachings of men". It grieved the disciples that Jesus had offended the reverend men from Jerusalem about their teaching: "washing hands before eating."
He charged these devout theologians with hypocrisy. Jesus showed that their tradition, which they reverenced as a revelation from God, led them into sin, and he disturbed their self complacency by showing that the ceremonial cleanness, which was founded on tradition, and in which they prided themselves, was worthless in comparison with the moral cleanness, required by God's law, which they ignored.
In verses 13-14 Jesus informs us that every plant His heavenly Father did not plant would be rooted up.
God had planted the law with its doctrine: he had planted the Hebrew religion as given by Moses. He had not planted the tradition of the elders; so it, and the religion founded upon it, was doomed to be rooted up.
Jesus makes a statement that has been bounced off the walls of most theological institutions in defense of their soteriology:
"Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall in the pit." Jesus, is here teaching that the disciple could expect to attain no higher felicity than his teacher. The words of Jesus are full of encouragement to those who adhere to the simple teachings of God; for his words here show that God guarantees that every error shall be uprooted, and every teacher of error or false religion shall participate in the judgment which uproots, and shall fall into the pit of ruin; and his disciples, no matter how numerous, shall share his fate.
Peter, in verse 15 asks for an interpretation of "this parable." I note that Jesus never calls his words here a parable. Peter is asking about Jesus' words in verse 11. "Not that which goes into the mouth defiles a man; but that which comes out of the mouth, this defiles a man."
The Pharisees had erred in confusing legal and spiritual defilement, and had added error to error by multiplying the cause of defilement in their tradition.
Question to you teachers of the higher persuasion.....In this teaching of Jesus in Matthew 15, is He speaking to a Jewish audience and referring to the destruction of Jerusalem as the "pit of ruin"? Are the "teachers" the Jewish leaders who would lead their disciples into it? Did God uproot their system of tradition or not? Was the pure gospel sowed in the room which they occupied?