Matthew 7:16-20

16By their fruit you will recognize them. Do people pick grapes from thornbushes, or figs from thistles? 17Likewise, every good tree bears good fruit, but a bad tree bears bad fruit. 18A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit. 19Every tree that does not bear good fruit is cut down and thrown into the fire. 20Thus, by their fruit you will recognize them.