In Matthew 7 Jesus tells us how to recognize false prophets: by their fruits. I am not a behavioral horticulturalist. I do not always know a good fruit from a bad fruit. What if a bad person has good intentions in doing a bad thing that has a good outcome? Or the reverse. What kind of tree are they and what kind of fruit are they? I don't always know. So why does Jesus say we “shall know them by their fruit?”
Although I am not a great spiritual horticulturalist, God is. He can look at a fruit and know exactly what kind of tree produced it. Someday He will take the trees that did not produce good fruit and dispose of them. And only then will I fully know every tree by their fruit.