Jesus wants his disciples to know that some people are bad for us.
One of Jesus’ teachings upsets the Pharisees and his disciples rush to tell him about it. “He answered, ‘Every plant that my heavenly Father has not planted will be rooted up. Let them alone; they are blind guides. And if the blind lead the blind, both will fall into a pit’”(Matt 15:13-14). Instead of worrying about their response, Jesus tells his followers to “let them alone.”
This thread is everywhere in Jesus’ teaching. “Do not give dogs what is holy, and do not throw your pearls before pigs, lest they trample them underfoot and turn and attack you”(Matt 7:6). He warns about people who are ravenous wolves in sheep’s clothing (Matt 7:15) and that disciples are “sheep in the midst of wolves”(Matt 10:16). When they encounter people who reject their message, they are to “shake off the dust from your feet when you leave that house or town”(Matt 10:14). He warns them of the “leaven of the Pharisees and Sadducees”(Matt 16:6). Some people are bad for us.
But this is not about elitism—or even primarily about influence. There are people who are dangerous to us. They will try to hurt us and exploit us and pollute us. We may initially think that we can influence them toward God, but repeated exposure only confirms that they continue to hurt us. They abuse our trust, ridicule our faith, manipulate us, exploit us, and hurt our feelings. They take our “pearls”—the things we value—and trample them, then turn to attack us. Listen to Jesus. “Let them alone.”
There are a few categories of people who Jesus singles out for this kind of treatment. There are those who are unwilling to listen (Matt 10:14). There are those who want their own desires and are willing to harm us to get them (Matt 7:15). There are those who are insincere in dealing with us because they have their own agendas (Matt 16:1-4). While there might be other examples of this kind of behavior, the point is that Jesus is teaching his disciples to use judgment in deciding that there are some people who need to be left alone.
Are there toxic people like this in your life? Listen to Jesus. As much as is possible, leave them alone.