Among the challenges to authentic Torah faith is the false prophet, a person who performs miracles, yet speaks in the name of idols:
If there will arise in your midst a prophet, or a dreamer of dreams, and he gives you a sign or a wonder. And then the sign or the wonder of which he spoke to you comes to pass, saying, “Let us go after other gods that you have not known, and let us serve them.” Do not listen to the words of that prophet, or to that dreamer of dreams, because Hashem, your G-d, is testing you, to know whether you love Hashem, your G-d, with all your heart and with all your soul. After (ACHAREI) Hashem, your G-d, shall you go, and Him shall you fear; His commandments shall you observe and to His Voice shall you listen, and to Him shall you cleave. But that prophet or that dreamer of dreams shall be put to death, because he has spoken falsehood against Hashem, your G-d, who brought you out from the land of Egypt and redeemed you from the house of slavery, to make you stray from the path that Hashem, your G-d, commanded you to go; and you shall destroy the evil from your midst (Devarim 13:2-6).

Verse 5 (underlined text) returns us to one of the central themes of the Book of Devarim: One’s devotion to Hashem must be complete and uncompromising. Even when this “prophet or dreamer” performs a wonder, he is not to be followed if he preaches for idol-worship. Rather,
After (ACHAREI) Hashem, your G-d, shall you go…
And after no one else. This is the basic reading of Saadiah Gaon.

Ohr HaChaim is puzzled by the insertion of this verse in the discussion about the false prophet. He, therefore, explains that each element of the verse enlightens us regarding the false prophet’s attempts:

• After (ACHAREI) Hashem, your G-d, shall you go – and not after idols. Do not accept upon yourself to follow other gods, but rather commit yourself wholeheartedly to obey only Hashem. “Going” refers to decision.

• And Him shall you fear – and not idols. Do not worry that these other gods will harm you. “Fear”, and reverence of Hashem must be exclusive.

• And His commandments shall you observe – and not the dictates of the other religions, even if they fall short of actual idol-worship. “Observing” refers to paying homage to the customs associated with idolatry.

• And to His Voice shall you listen – and not to the teachings of idolatry. “Listening” is learning, and there is no greater learning than Hashem’s Torah.

• And Him shall you serve – No “service,” no worship, is due any but Hashem. One must not even accede to the prophet’s recommendation to appear to worship idols. In this connection, Ohr HaChaim cites the story (Gitten 57b) of Chanah and her seven sons. The king suggested that the youngest son give the appearance of bowing before the idol while actually bending to pick up a ring that the king dropped, but the lad refused.

• And to Him shall you cleave  “Cleaving” to Hashem (see Ketubot 111b) means attaching oneself to those who learn Torah, not to those who serve idols.

The Torah follows this with the punishment of the false prophet. This, says Ohr HaChaim is to indicate that if the prophet “speaks” any of the “falsehoods” implied here – whether he speaks of deciding to follow idols, or of fearing them, or of practicing their customs, or of learning about them, or of worshipping them, or of studying with their devotees – he is deserving of death. But the initial suggestion, considering idols as an alternative truth, is the root of all this evil.

Other commentaries focus on the positive teachings of the verse regarding commitment to Hashem. “Following” Hashem, says Ramban, is seeking to learn His Will through His prophets, while “fearing” Him means knowing that He alone possesses the power over life and death, reward and punishment, and forgiveness. “His commandments” means the Torah of Moshe. “His Voice” is heard through the dictates of His true prophets, while “serving” Hashem is the worship in the Sanctuary (Rashi and Ramban, based on Sifri 85). Finally, says Rashi (based on Sotah 14a), one “cleaves” to Hashem by emulating His acts of kindness, such as burying the dead and visiting the sick.

The Chafetz Chaim (Rabbi Yisrael Meir Kagan) raises a question regarding the first word in our verse, ACHAREI. In his commentary to Bereishit 15:1, Rashi adopts a principle from Midrash Bereishit Rabbah 44:5 to distinguish between the two Hebrew words for “after”:
“Whenever it says ACHAR it means ‘immediately after,’ while ACHAREI means ‘much later.’”

Based on this, our verse becomes difficult. Should we not be enjoined to follow Hashem closely, to try to be as intimate in our knowledge and devotion to Him as we can? If so, the verse should have said
“ACHAR – after – Hashem, your G-d, shall you go…”
Why does it use the word, ACHAREI connoting distance?

The answer of the Chafetz Chaim shows deep insight into the human condition. There are many times that a person senses a detachment from Hashem, that he is Acharei, very far from His Presence. Anything can bring this on: sin, laziness, or personal tragedy. It is at these times, when one is ACHAREI – at a great distance from Hashem – that one may despair of ever regaining a sense of His closeness again.

But, despair is not the solution. When one is ACHAREI, then he must continue to pursue Hashem, to revere Him from the position of beholding the “mysterium tremendun” and to obey His commands. Then he will be uplifted to the point of feeling he is a servant of Hashem, cleaving once again to Him.

The false prophet, especially one who purports to speak in Hashem’s Name, may pose one of the most profound challenges to our individual and national connection to Hashem. However, if we seek Him, from whatever abyss of gloom we may find ourselves, we can return in triumph to Hashem’s loving embrace.