Jesus did not come to form an exclusive club. He did not come to form a social organization that would be very selective about the people allowed to join. Jesus came to call all who would listen and observe what he did to join him by doing the same and telling others about him.
A group of disciples believed in him and followed him. They knew Jesus and they knew one another. He sent them out to preach and heal people in need. They returned with reports of the great things they accomplished in his name. When they saw people who were not in their group doing other great things in the name of Jesus, they tried to stop them. We can imagine them thinking, “Who do they think they are? They are not members of the club. We should stop them.”
Jesus is teaching us that attitudes of exclusivity, elitism, superiority and authoritarianism cause us to sin. He cautions us that if parts of our bodies or self-centered attitudes cause us to sin, CUT THEM OFF of our bodies or CUT THEM OUT of our life. Do we need to do any cutting?