In the remaining verses of the chapter, verses 20-22, the subject matter changes. God seems to acknowledge that He has purposely left the true Prophet unnamed, perhaps wanting His people to put effort into recognizing the Prophet or prophets who truly represent Him. Of course, He wants us to use His criteria, which He proceeds to explain. This is just as true today as it was in ancient Israel.
The "generic" prophet mentioned here does not refer specifically to the Prophet of God of the previous verses. The Bible translators seem to have picked up on this point and have highlighted it by capitalizing "Prophet" in verses 15 and 18, but leaving it in lower case in verses 20 and 22. These latter verses seem to refer to any prophet—true, professing, and even false prophets. Verse 20 warns that, if a man calling himself a prophet claims to speak in God's name but speaks words that God has not given him or speaks in the name of false gods, he puts himself under the death penalty.
If a man falsely claims to speak in God's name, or if he speaks in another god's name, he is worthy of death. If the man's predictions do not occur, he is a false prophet. Conversely, if a man speaks in God's name, and what he says happens, he may indeed be a true prophet (Jeremiah 28:8-9).
Apart from Christ Himself, Ezekiel may be the clearest case of a true prophet. He prefaces many of his prophecies with "the word of the LORD came to me, saying . . ." (Ezekiel 3:16; 6:1; etc.), followed by a direct quotation of God's words. This is speaking "a word in My name" (Deuteronomy 18:20). If it is indeed what God commanded him to say, he is guiltless, whether or not it comes to pass within his lifetime. Many of Ezekiel's prophecies, for instance, had a near fulfillment (in type) and a far fulfillment (antitype). In both cases, he is shown to be a true prophet of God.
Richard T. Ritenbaugh
Was Herbert Armstrong a False Prophet?
Other Forerunner Commentary entries containing Deuteronomy 18:20: