"Watch out for false prophets. They come to you pretending to be sheep. But on the inside they are hungry wolves.
References for Matthew 7:15
You can tell what they really are by what they do. "Do people pick grapes from bushes? Do they pick figs from thorns?
In the same way, every good tree bears good fruit. But a bad tree bears bad fruit.
A good tree can't bear bad fruit. And a bad tree can't bear good fruit.
Every tree that does not bear good fruit is cut down. It is thrown into the fire.
You can tell each tree by its fruit.