John Wesley on Matthew 13:28

He said, An enemy hath done this - A plain answer to the great question concerning the origin of evil. God made men (as he did angels) intelligent creatures, and consequently free either to choose good or evil: but he implanted no evil in the human soul: An enemy (with man's concurrence) hath done this. Darnel, in the Church, is properly outside Christians, such as have the form of godliness, without the power. Open sinners, such as have neither the form nor the power, are not so properly darnel, as thistles and brambles: these ought to be rooted up without delay, and not suffered in the Christian community. Whereas should fallible men attempt to gather up the darnel, they would often root up the wheat with them.