Theology as Seen in Prophets and Psalms/Nature of Prophets and Prophecy
Dtr 18:20-22 Is the Biblical test for false prophets and false prophecy. A false prophet either speaks for false gods or attributes to the Lord things that the Lord did not command him to speak. The criteria for prophecy is thus: One; It must be uttered in the name of the Lord. The Message Formula gives the clue that this is not just an opinion or an off-the-wall comment by a prophet. So, with out the marker it cannot be taken as a prophecy, pretended or otherwise. Only when he/she is delivering the word of the Lord. Two; The prophecy must not fail. But no timeframe is established for the fulfillment of a prophecy. This is very subjective. If however, a known prophet of God proclaimed that X would happen because God said it would then faith would follow that it will occur. Now the Deuteronomy test doesn't say that a man is a false prophet because his prophecy failed, only that the failed prophecy is false. This being the case, it is incorrect to conclude, that one false prophecy makes for a false prophet. The danger in so defining the Deuteronomy test is a tendency to "explain away" the prophecy and thus the prophet. The work is done for us, however, the process of determining the truth or falseness of a prophet would be completely subjective were it not for the fact that certain words of true prophets are canonnized.
This may seem like proving something by saying it is so. To that I would say that it is faith that determines belief and not belief that determines faith.