" Earlier in this same chapter, Jesus has related a significant little story commonly called the parable of the tares and wheat (Matthew 13:24–30, 36–43). Both had been allowed to grow together until the harvest, but then the reapers were to gather them up in bundles. The tares were to be burned; the wheat gathered. We often wonder why God permits so much sin in the world, why He withholds His right arm of judgment. Why doesn’t God put an end to sin now? We can give an answer from this text where Jesus said, “Let both grow together,” the evil with the good (verse 30). If we were to try to wipe all evil from the face of the earth, who could count on justice? Pure justice does not exist here, because everyone is guilty, including the judges who sit in judgment. We are all guilty of sin. Man must do his best in meting out "
― Billy Graham , Angels: God's Secret Agents