Many muslims use Deuteronomy 18 to say Mohammad was the messenger as spoken through Moses, because the quran says muslims can find him revealed in there.
Yet God said to Moses in Deuteronomy 18
"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."
Mohammad gave a revelation saying people could worship 3 godess's, then later denounced it saying the revelation was not from God but satan. He spoke of other gods in the name of God that was not from God only later to say he made a mistake.
Deuteronomy 18 only proves Mohammad a false prophet.