One interesting thing about a Dallas Cowboys football game is that if you don’t have a ticket, you don’t get in. The ticket qualifies you to enter the stadium and sit in a particular seat. In a similar way, avoiding ritual defilement was necessary in the time of Jesus to enter the temple and worship God. Those who were defiled, according to the law, were not qualified to enter and worship.
Because the temple was central to the worship of God, a great deal of rabbinic teaching existed to define defilement and to spell out how to eliminate it. You would think that defilement would be the one thing that all Jewish religious leaders understood. But Jesus refuted that belief.
10 Jesus called the crowd to him and said, Listen and understand. 11 What goes into someones mouth does not defile them, but what comes out of their mouth, that is what defiles them.
12 Then the disciples came to him and asked, Do you know that the Pharisees were offended when they heard this?
13 He replied, Every plant that my heavenly Father has not planted will be pulled up by the roots. 14 Leave them; they are blind guides. If the blind lead the blind, both will fall into a pit.
When Jesus summons the crowd to listen and understand (verse 10), that sets the stage for an escalation of the conflict between him and the Jewish religious leaders. What Jesus says in verse 11 seems simple enough to us, but it directly contradicted the teaching of the Jewish religious leaders about defilement. They claimed that defilement came from external sources, but Jesus said that what emerges from the mouth, from the inside of a person, is what defiles that person.
When we get to verse 18, Jesus will identify the exact inner source of what defiles a person.
Presumably some time passed after Jesus spoke to the crowd (verse 11), and during that time the Pharisees were seething and deeply offended over what Jesus had said about defilement. The disciples quickly learned of this development and went to Jesus to warn him of it (verse 12). The disciples show the respect many must have felt toward a high-level delegation of religious leaders from Jerusalem.
Jesus answers the news with a surprising metaphor: Every plant that my heavenly Father has not planted will be pulled up by the roots (verse 13). Since the traditions of the Pharisees contradict the commandment of God, they are the ones who can expect to be pulled up by the roots! This language may well look back to the Parable of the Weeds, where Jesus taught about the separation that will take place at the final judgment. Jesus disciples are the plants established by God, not the Pharisees and their allies.
As to how they might relate to the offended Pharisees, Jesus tells his disciples, Leave them (verse 14a), with the idea of abandoning them and going on to something else. This Greek verb is also used for divorce. In offering his reasons for this action, Jesus returns to metaphors: They are blind guides. If the blind lead the blind, both will fall into a pit (verse 14b). In the arid climate of Palestine, cisterns were dug underground and lined with stone. The surface entry was often a terrible hazard for those unable to see.
Ritual purity, and therefore defilement, held extreme importance to the Pharisees. Jesus has already crossed the boundary of propriety by touching women, lepers and even the dead in order to heal them. Now he moves from deed to word in teaching that defilement comes from within, not from externals. R. T. France explains the significance by saying, After this dialogue the breach between Jesus and the scribal establishment is irreparable.
Copyright 2015 by Barry Applewhite, Plano, Texas. All rights reserved worldwide. Materials originally developed for Christ Fellowship, McKinney, Texas. Used by permission.
 Passages such as Isaiah 5:1-7 contain similar ideas.
 R.T. France, The Gospel of Matthew, The New International Commentary on the New Testament (Grand Rapids: William B. Eerdmans Publishing Company, 2007) 575.