"It's not his fault that his prophecy didn't come true; he just misunderstood what he heard from the Lord. People are allowed to be wrong sometimes, aren't they?" Having gone to mostly Pentecostal churches since getting saved, I have heard this line of reasoning over, and over, and over. Some preacher or leader would speak 'a word' over somebody's life, and it wouldn't come to pass. Then they would make the same mistake the next time. Then again. And who know how many times after that? And this line of reasoning is widespread! - when failed (false) prophet Harold Camping predicted the end of the world on May 21st, 2011, lots of people cited Matthew 24.36 as a reason for not believing him, but few if any cited Deuteronomy 18.22 and connected it with Camping's failed prophecy in 1994. That Old Testament passage says,
"When a prophet speaks in the name of the LORD, if the word does not come to pass or come true, that is a word that the LORD has not spoken; the prophet has spoken it presumptuously. You need not be afraid of him."
Deuteronomy 18.22 on Failed Prophecies and False Prophets
Read this passage with me: First, if a prophet speaks in the name of Yahweh and that prophecy does not come true, then we do not need to be afraid of that prophet or honor him. When do you and I stop fearing or honoring the failed prophet? After his failed prophecy. The clear meaning of this passage is that if a prophet fails, we should never listen to him again. (The immediate context is more harsh; if a prophet speaks a word that turns out not to have come from Yahweh, the Israelis were supposed to stone that prophet to death.)
New Testament Prophets Are Different - Aren't They?
There is no evidence that says prophets today should be held to a different standard than prophets in Old Testament times. There is no passage, for example, where Peter, Paul, or John write to the churches saying,you know what? Sometimes legitimate prophets make mistakes. God's just into making faulty prophets now - so give the guy a break.
Some people think that Old Testament prophets couldn't make mistakes because God had them write books of the Bible, and that -supposedly- was the only reason for these kinds of requirements. But, (1) Deut. 18.22 applies to all prophets, and not every prophet in the Old Testament wrote books of the Bible: Gad (1 Samuel 22.5), Nathan (2 Samuel 7.2), Ahijah (1 Kings 11.29), Jehu (1 Kings 16.7), and Elijah (1 Kings 18.36) are all Old Testament prophets who never wrote books of the Bible; (2) At least one New Testament prophet wrote a book of the Bible as well - John the Apostle (or John the Elder), who wrote Revelation.
Last Argument (For Now): God Does Not Change
There is no denying that something special happened on Pentecost. Even though the disciples had already been given the Spirit before then (John 20.21-23), the gifts of the Spirit came on that day in a greater degree than ever before. The proportion of people who received gifts of the Spirit (entire churches) and the variety of those gifts (healing, tongues, prophecy, etc.) was greater than ever before. The Spirit was definitely with the New Testament Church in a bigger way than He had ever been with Old Testament Israel.
But in the midst of all this excitement, God did not change. As Christians, we're supposed to believe that God is the same yesterday, today, and forever (Hebrews 13.8), right? So God did not change. He did not decide one day to start giving the Church faulty prophets, who could not figure out the difference between His voice and their own imaginations. He did not stop being angry with so-called prophets who speak in His name out of their own imaginations (Jeremiah 23.16; Jeremiah 23.19). He did not stop commanding that His people refuse to listen to failed prophets - in fact, there is no New Testament passage that says we should listen to them.
The Line In the Sand
Look, if you or a someone you respect thinks that they hear prophetic words from the Lord, I don't doubt your sincerity. But I have to listen to what the Bible says, not you, and if you have failed in even one prophetic utterance, then the Bible says that you are wrong to call yourself a prophet. It says that God does not speak through you. It says that I should not listen to you. It says that you are dishonoring God by speaking, in His name, out of your own imagination. That's what it says.
God has not changed and started to give us faulty prophets; New Testament prophets are not demonstrably different than Old Testament ones; the Bible places a high standard on those who claim the prophetic gift, and nowhere does it go back on that standard.
If you are following someone who does not fit the Biblical requirement for a prophet, get out of that situation before things go bad. If you fit the Biblical definition of a false, failed prophet, and you're just realizing it now, repent publicly and do not claim to prophesy again; ask God's forgiveness and shut down your public ministry until you get your head straight.
This is a serious issue.
------------------------------------------------------------------------------*The title picture is of public figure and Christian television personality Pat Robertson, who wrongly predicted that the world would end in 1982. He still claims to receive prophetic words from God.