15Beware of false
prophets, which come to you in sheep’s clothing, but inwardly they are ravening wolves.
 16Ye shall know them by their fruits. Do men
gather grapes of thorns, or figs of thistles?  17Even so every good tree bringeth forth good fruit; but a corrupt tree
bringeth forth evil fruit.  18A good tree
cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.  19Every tree that bringeth not forth good fruit is hewn
down, and cast into the fire.  20Wherefore
by their fruits ye shall know them. (Matthew
7:15-20, King James
Version)