For such men are false apostles, deceitful workmen, disguising themselves as apostles of Christ. And no wonder, for even Satan disguises himself as an angel of light. So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds.
II Corinthians 11:13-15 (ESV)
Topics and Links are arranged in alphabetical order.
There are many offshoots of the 'church' that Joseph Smith founded. However, if Joseph Smith is a false prophet then all the 'churches' that base their faith on the Book of Mormon are false too.
Joseph Smith's False Prophecies
"But the prophet who shall speak a word presumptuously in My name which I have not commanded him to speak, or which he shall speak in the name of other gods, that prophet shall die.’ "And you may say in your heart, ‘How shall we know the word which the Lord has not spoken?’ "When a prophet speaks in the name of the Lord, if the thing does not come about or come true, that is the thing which the Lord has not spoken. The prophet has spoken it presumptuously; you shall not be afraid of him." (Deut. 18:20-22). emphasis added.
There are many web sites discussing this, this is just one example. Note the first example, it only takes one false prophecy to make a 'prophet' false.