The Prophet and False Prophets
Israel is again cautioned against learning "to follow the abominations" of the people living in the land, including the practices of witchcraft, sorcery or divination (verses 9-14). In contrast to pagan soothsayers, Moses prophesies that God would eventually raise up a Prophet like himself, referring to the coming of Jesus Christ (verses Deuteronomy 18:15-19 Deuteronomy 18:15-19  The LORD your God will raise up to you a Prophet from the middle of you, of your brothers, like to me; to him you shall listen;
 According to all that you desired of the LORD your God in Horeb in the day of the assembly, saying, Let me not hear again the voice of the LORD my God, neither let me see this great fire any more, that I die not.
 And the LORD said to me, They have well spoken that which they have spoken.
 I will raise them up a Prophet from among their brothers, like to you, and will put my words in his mouth; and he shall speak to them all that I shall command him.
 And it shall come to pass, that whoever will not listen to my words which he shall speak in my name, I will require it of him.
American King James Version×; see John 1:45 John 1:45Philip finds Nathanael, and said to him, We have found him, of whom Moses in the law, and the prophets, did write, Jesus of Nazareth, the son of Joseph.
American King James Version×; Acts 3:22-23 Acts 3:22-23  For Moses truly said to the fathers, A prophet shall the Lord your God raise up to you of your brothers, like to me; him shall you hear in all things whatever he shall say to you.  And it shall come to pass, that every soul, which will not hear that prophet, shall be destroyed from among the people.
American King James Version×). He makes clear that just as the words from God that he proclaimed were to be obeyed, so it would be with this future Prophet. And indeed, like Moses, Jesus came as an Announcer of God's law and as a Mediator of a covenant based on that law. In short, Christ's words were to be followed—whereas others who would falsely claim to be prophets would have to be rejected (Deuteronomy 18:20 Deuteronomy 18:20But 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.
American King James Version×).
Christ would later confirm that many false prophets would come to deceive the many (compare Matthew 24:4-5 Matthew 24:4-5  And Jesus answered and said to them, Take heed that no man deceive you.
 For many shall come in my name, saying, I am Christ; and shall deceive many.
American King James Version×, 11). Sadly, this problem has always persisted among God's people (2 Peter 2:1-3 2 Peter 2:1-3  But there were false prophets also among the people, even as there shall be false teachers among you, who privately shall bring in damnable heresies, even denying the Lord that bought them, and bring on themselves swift destruction.  And many shall follow their pernicious ways; by reason of whom the way of truth shall be evil spoken of.  And through covetousness shall they with feigned words make merchandise of you: whose judgment now of a long time lingers not, and their damnation slumbers not.
American King James Version×). Moses gives a clue as to how to determine whether a person is a prophet of God or not: "When a prophet speaks in the name of the Lord, if the thing does not happen or come to pass, that is the thing which the Lord has not spoken; the prophet has spoken it presumptuously" (Deuteronomy 18:22 Deuteronomy 18:22When a prophet speaks in the name of the LORD, if the thing follow not, nor come to pass, that is the thing which the LORD has not spoken, but the prophet has spoken it presumptuously: you shall not be afraid of him.
American King James Version×). But one word of caution here: Sometimes, false prophets will foretell the future accurately (see Deuteronomy 13:1-5 Deuteronomy 13:1-5  If there arise among you a prophet, or a dreamer of dreams, and gives you a sign or a wonder,  And the sign or the wonder come to pass, whereof he spoke to you, saying, Let us go after other gods, which you have not known, and let us serve them;  You shall not listen to the words of that prophet, or that dreamer of dreams: for the LORD your God proves you, to know whether you love the LORD your God with all your heart and with all your soul.  You shall walk after the LORD your God, and fear him, and keep his commandments, and obey his voice, and you shall serve him, and join to him.  And that prophet, or that dreamer of dreams, shall be put to death; because he has spoken to turn you away from the LORD your God, which brought you out of the land of Egypt, and redeemed you out of the house of bondage, to thrust you out of the way which the LORD your God commanded you to walk in. So shall you put the evil away from the middle of you.
American King James Version×)—and God Himself may even be behind it (see Numbers 22:20 Numbers 22:20And God came to Balaam at night, and said to him, If the men come to call you, rise up, and go with them; but yet the word which I shall say to you, that shall you do.
American King James Version×, Numbers 22:38 Numbers 22:38And Balaam said to Balak, See, I am come to you: have I now any power at all to say any thing? the word that God puts in my mouth, that shall I speak.
American King James Version×; Numbers 23:12 Numbers 23:12And he answered and said, Must I not take heed to speak that which the LORD has put in my mouth?
American King James Version×). Yet even if someone relays many correct prophecies, the verse quoted above basically tells us that if there is just one instance where he claims that God has, apart from Scripture, specially and directly communicated to his mind regarding some event that will happen and the event does not come to pass as he proclaimed it would, that alone would make him a false prophet—that is, unless the proclamation is a warning of divine punishment and those to whom it is directed repent, as all such prophecies are contingent upon whether the recipients repent or not (compare Jeremiah 18:6-8 Jeremiah 18:6-8  O house of Israel, cannot I do with you as this potter? said the LORD. Behold, as the clay is in the potter's hand, so are you in my hand, O house of Israel.  At what instant I shall speak concerning a nation, and concerning a kingdom, to pluck up, and to pull down, and to destroy it;  If that nation, against whom I have pronounced, turn from their evil, I will repent of the evil that I thought to do to them.
American King James Version×; Jonah 3:1-10 Jonah 3:1-10  And the word of the LORD came to Jonah the second time, saying,  Arise, go to Nineveh, that great city, and preach to it the preaching that I bid you.  So Jonah arose, and went to Nineveh, according to the word of the LORD. Now Nineveh was an exceeding great city of three days' journey.  And Jonah began to enter into the city a day's journey, and he cried, and said, Yet forty days, and Nineveh shall be overthrown.  So the people of Nineveh believed God, and proclaimed a fast, and put on sackcloth, from the greatest of them even to the least of them.  For word came to the king of Nineveh, and he arose from his throne, and he laid his robe from him, and covered him with sackcloth, and sat in ashes.  And he caused it to be proclaimed and published through Nineveh by the decree of the king and his nobles, saying, Let neither man nor beast, herd nor flock, taste any thing: let them not feed, nor drink water:  But let man and beast be covered with sackcloth, and cry mightily to God: yes, let them turn every one from his evil way, and from the violence that is in their hands.  Who can tell if God will turn and repent, and turn away from his fierce anger, that we perish not?  And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do to them; and he did it not.
American King James Version×). And, of course, as explained in the highlights for Deuteronomy 13, someone's fulfilled prophecies are to be measured against his teachings and deeds. We are never to follow anyone's anti-biblical teachings or evil practices.