"Beware of false prophets who come disguised as harmless sheep but are really vicious wolves. You can identify them by their fruit, that is, by the way they act. Can you pick grapes from thornbushes, or figs from thistles? A good tree produces good fruit, and a bad tree produces bad fruit. A good tree can't produce bad fruit, and a bad tree can't produce good fruit. So every tree that does not produce good fruit is chopped down and thrown into the fire. Yes, just as you can identify a tree by its fruit, so you can identify people by their actions.