"Beware of false prophets, who come to you in sheep's clothing, but underneath are ravenous wolves. By their fruits you will know them. Do people pick grapes from thornbushes, or figs from thistles? Just so, every good tree bears good fruit, and a rotten tree bears bad fruit. A good tree cannot bear bad fruit, nor can a rotten tree bear good fruit. Every tree that does not bear good fruit will be cut down and thrown into the fire. So by their fruits you will know them. (Mt 7:15-20)
False Prophets were persons who claimed to be speaking the word of God but in fact they were not. They were very nice people, very reasonable and in fact trust worthy people. People also listened to the happily. But they were leading the people in the wrong way.
There was no test to find out the true Prophet from a false Prophet. Only test was to wait for the prophecies to be fulfilled. Prophecy is the prophet. Prophet can be identified as true or false only after the fulfilment of the prophecy. Prophecy has to be seen being fulfilled in the life of the prophet. His life will be reveal.
Jesus gives a graphic example of a tree and its fruits. Looking at the tree we cannot say anything. A tree may look good and healthy but only the fruits will reveal the tree completely. Jesus also gives a hint that the true and the false prophets will be treated according to deeds.
