For a good tree does not bear bad fruit, nor does a bad tree bear good fruit. Luke 6:43
There is a long list of modern metaphors and sayings that have their origin in the Bible. One of the most widely known is the picture of a wolf disguising itself as a sheep: a wolf in sheep’s clothing. That image comes from Jesus (not from the fables of the Greek Aesop), meaning you can’t judge people by how they appear but rather by the evidence of their life.
In the same sermon, Jesus paralleled that image with another—the kind of fruit a tree bears: “You will know them by their fruits” (Matthew 7:16). He went on to expound that grapes don’t come from thorn bushes or figs from thistles. Only “good” trees bear “good” fruit, and “bad” trees bear “bad” fruit. These weren’t lessons on raising sheep or harvesting fruit, they were lessons about people. The works or fruit or actions of a person ultimately will reveal who he or she truly is. As Paul would later put it, these are the works of the flesh or the fruit of the Spirit (Galatians 5:16-26).
These ancient metaphors are directly relevant for us. If our walk does not match our talk, we will eventually be found out by the type of fruit we produce for the Lord.
Fruit is evidence of the root. John Blanchard