Matthew 7:15-16 says “Beware of false prophets who come disguised as harmless sheep, but are really wolves that will tear you apart. You can detect them by the way they act, just as you can identify a tree by its fruit.” The Greek words used to translate in our pew Bibles for “by the way they act” means “by their fruit.” In other words you can tell false prophets by their fruits. I once heard someone preach on these verses as saying the fruits are the fruit of the spirit. I do not think the lack of the fruit of the spirit is a mark of the false prophet. What we need to do is to check out the scriptures to see what the fruits of false prophets are.
The role of the prophet is to either forth tell or foretell. In other words to either preach God’s truth or to prophesy a future event. Deuteronomy 18:20-22 describes a false prophet as giving “a message from another god or who falsely claims to speak [for God]” or “predicts something in the Lord’s name and it does not happen.” These are the fruits of a false prophet. Another passage you might check out is Deuteronomy 13:1-5.
Joseph Smith provides an excellent example of both roles he tried to fulfill as a self-proclaimed prophet. In his Book of Mormon there is the phrase, “You are saved by grace after all you can do.” A person can always do more. Also, if you have to work at it, is it really grace? In another work attributed to Joseph he claimed Christ would come back in 1891. If you had not noticed, he missed the mark. One false prophecy makes a false prophet.
I had almost become entrapped by the Jehovah Witnesses over 40 years ago. After discovering the false teachings and false prophecies I steered clear of them. Since that time 40 years ago I have put together documents from both Mormon publications and from Jehovah Witnesses publications showing the problems of both groups. If interested, come see me or contact me by email: email@example.com.