 Jesus tells us to judge the fruit of teachers in order to recognize false teachers. He says in Matthew 7, Beware of false prophets who come to you in sheep's clothing, but inwardly are ravenous wolves. You will recognize them by their fruits. St. Paul tells us to judge ourselves, lest we eat the sacrament unworthily. He writes in 1 Corinthians 11, But if we judged ourselves truly, we would not be judged.