When I was growing up in Mormonism, I was taught that God would never allow a prophet to lead the church astray.
Yet, recent statements from the Mormon Church seem to contract this teaching when they say, “… we must be worthy and receive inspiration from the Holy Ghost in order to know when the Brethren speak by the power of the Holy Ghost…” The Church manual, Teachings of the Living Prophets, then says, “In a way, this completely shifts the responsibility from them to us to determine when they so speak” by the Holy Ghost.” So, if it’s up to us, individuals, to determine if a prophet is speaking from God, then what’s the point of having a living prophet leading the Church in the first place?
In the Bible, God warns that if a prophet “…shall presume to speak a word in my name, which I have not commanded him to speak, …even that prophet shall die. … When a prophet speaketh in the name of the LORD, if the thing follow not, nor come to pass, that is the thing which the LORD hath not spoken….” So the Bible is clear. There is no room for God’s prophets to give revelations that are not from Him.
So, did Joseph Smith give false revelations?
History shows that he did. Doctrine and Covenants records two temple prophecies that failed when Mormons were driven out of Missouri (See Doctrine and Covenants Sections 84 and 115). And in Doctrine and Covenants Section 103, Joseph Smith received a revelation to form a group of men, called Zion’s Camp, to reclaim their Missouri land. But the mission failed miserably with men dying of sickness along the way.
Reading these false prophecies, which never came to pass, we can see that history proves Joseph Smith was not a true prophet sent from God, so Mormonism cannot be true.
Some Mormons argue that the reason the Zion’s Camp prophecy failed was due to some type of unfaithfulness among the LDS saints as the revelation says, “All victory and glory is brought to pass unto you through your diligence, faithfulness, and prayers of faith.” (D&C 103:36) Yet, historical documents do not reveal a single way in which they were unfaithful. In every aspect, they carried out the demands perfectly. So claiming unfaithfulness on the part of the saints doesn’t justify this false prophecy.
 See statements of President Wilford Woodruff quoted in Gospel Principles, Chapter 9: Prophets of God.
 See Teachings of the Living Prophets Student Manual, Chapter 6: General Conference, p. 73.
 Deuteronomy 18:20-22