Every Good Tree..Good Fruit. Corrupt, Evil

Mat 7:17 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
Mat 7:18 A good tree cannot bring forth evil fruit, neither [can] a corrupt tree bring forth good fruit.
Mat 7:19 Every tree that bringeth not forth good fruit is hewn down, and cast into the fire.
Mat 7:20 Wherefore by their fruits ye shall know them.