Deuteronomy 18:20,21 (KJV)
20 But the prophet, which shall presume to speak a word in my name, which I have not commanded him to speak, or that shall speak in the name of other gods, even that prophet shall die.
21 And if thou say in thine heart, How shall we know the word which the Lord hath not spoken?
Mormons Take 1 Corinthians 15:29 Out Of Context
The verse that Mormons take out of context in the Bible, more than any other, comes in 1 Corinthians 15, verse 29.