Many false prophets. But Jesus left instructions. Know them by their fruits:

[15]Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.

[16] Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?

[17] Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.

[18] A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.

[19] Every tree that bringeth not forth good fruit is hewn down, and cast into the fire.