Why would Jesus talk to his followers about fruit? How many of you are those trees that they cut down and burn?

You will know them by their fruits. Gs are not gathered from thorn bushes, nor figs from thistles, are they? Even so, every good tree bears fruit; but the bad tree bears bad fruit. A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. So then, you will know them by their fruits. (Matthew 7:16-20)