Jesus shared a parable about a sower who sowed good seed in a field but an enemy came and sowed weeds among the wheat. Common agricultural sense is that the crops were ruined and the servants told their master that, in essence, they would help start the sowing again. Instead, the master said to let them both grow until the harvest time. Then the weeds can be sorted from the wheat.
Jesus is tackling the age-old issue of how to repond to the evil of the world. Contrary to Christian history, the teaching suggests that the Church should not retaliate nor act violence to evil. Instead, evil is to be tolerated until God removes evil in the final judgment.
Consequently, we are not to judge others. In fact, our judgments can do more harm than our perceived good actions. Let God and God alone judge.
Yet, we need to remember that each one of us has characteristics that are both "wheat" and "tares" in our lives. We oscillate from living in the Spirit and living in the flesh.
This leads us to a new definition of evil: Evil in our lives is anytime we say we can navigate this world and fix ourselves without the hand of God directing us.
Moreover, obsessing about the tares in our lives is the lie. Release judgment of ourselves and accept God's judgment on us. In Christ, He pronounces us as righteous. In the end, that is all that matters.