No sin is as antithetical to the Torah as idolatry. Moshe repeatedly warns Israel against any temptation to idol-worship. Between the admonitions regarding the false idolatrous prophet (Devarim 13:2-6) and Ir ha’nidachat, the city that has gone astray into idolatry (13:13-19), we learn of the meisit, the enticer:

If your brother, son of your mother, or your son or your daughter, or the wife of your bosom, or your friend who is like your own soul will entice you in secret, saying: “Let us go and serve other gods”, which neither you nor your fathers have ever known, of the gods of the nations that are around you, those close to you or those far from you, from one end of the earth to the other end of the earth. Then you shall not consent to him, nor shall you listen to him, nor shall your eye spare him, nor shall you exonerate, nor shall you conceal for him. Rather, you shall surely kill him; your hand shall be against him first to execute him and the hand of all the people later. And you shall stone him with stones so that he dies, because he sought to lead you astray from upon (MEI’AL) Hashem, your G-d, Who brings you out from the land of Egypt, from the house of bondage. And all Israel shall hear, and fear, and they shall not continue to do such a thing in your midst (verses 7-12).

The meisit might be anyone influential, even a close relative or dear friend. Such people arouse our compassion, our protective instincts; we might not want to report them, hoping instead to change their minds.

As the verse says, the meisit entices ba’seiter, in secret. Still, witnesses are required for conviction. Meisit is one of four criminals (the others being the rebellious son, the rebellious elder and the scheming witnesses) whose execution is publicized (Sanhedrin 89a).

Sefer HaChinuch (ascribed to either R. Aharon HaLevi or R. Pinchas HaLevi of Barcelona, mid-13th Century) identifies six mitzvot here:
§ 457: to have no affection for an enticer
§ 458: not to relinquish hatred for an enticer
§ 459: not to rescue an enticer from death
§ 460: the enticed person shall not speak in favor of the enticer
§ 461: the enticed person shall not remain silent from finding the enticer’s guilt
§ 462: not to entice an Israelite toward idol-worship

Rashi’s comments (v.9, which we paraphrase) further demonstrate the severity of the laws of the meisit:
– Then you shall not consent to him: Regarding all other Jews [including convicted criminals about to be executed (Sanhedrin 45a)], it is said, “And you shall love your fellow as yourself” (Vayikra 19:18). But you shall not love the meisit.
– Nor shall you listen to him: when he begs for his life for you to forgive him. Regarding all others [including sinners], it is said, “You shall surely assist him” (Shemot 23:5). But you shall not help the meisit.
– Nor shall your eye spare him: Unlike others, of whom it is said, “You shall not stand by your brother’s blood” (Vayikra 19:16), you shall not spare the meisit.
– Nor shall you exonerate: Do not look for excuses for him, or seek ways of acquitting him.
– Nor shall you conceal for him: If you are aware of arguments in favor of conviction, you are forbidden to remain silent about them.
– Rather, you shall surely kill him: Contrary to all other capital cases, if he leaves the courtroom guilty, do not bring him back if you think of arguments for acquittal; if he leaves the courtroom innocent, return him to argue for conviction.
– Your hand shall be against him first: Unlike other cases, where the witnesses throw the first stone (Devarim 17:7), it is the obligation of the one enticed to execute him [since he might be a relative, he cannot serve as a witness].

These laws are codified in Rambam “Laws of Idolatry” (5:1-5). He adds that a meisit can be entrapped into speaking before witnesses. Also, meisit is the only instance in Torah law where we conceal witnesses to listen in on him without forewarning him.

The meisit is executed for merely attempting to entice, even if he did not succeed. The laws of meisit are so grave that they override all relations with fellow-Jews.

Why is this so?

Rashi (v.7) points out the disgraceful irony of
Which neither you nor your fathers have ever known.
Whereas other nations do not reject what they have received from their ancestors, this enticer wants you to reject the G-d of your fathers-what a disgrace!

In addition, Meshech Chochmah (R. Meir Simcha of Dvinsk 1843-1926) focuses on
because he sought to lead you astray from upon (MEI’AL) Hashem, your G-d.
According to the Talmud (Berachot 6a), the verse, And all the nations of the earth shall see that the Name of Hashem is called upon you (Devarim 28:10) refers to our tefillin of the head, which is our glory. Hashem, too, wears tefillin in which is written, And which one nation is like Your people Israel? (Divrei HaYamim I 17:21). Hashem praises Israel just as Israel praises Him:
The Holy One blessed be He said to Israel, “You have made Me unique in the world. I will likewise make you unique in the world.”
Says Meshech Chochmah:
“The enticer to idolatry wants to remove them from being Hashem’s glory, and from being inscribed in His tefillin.”

More than any other idolater, the meisit undermines the union of Hashem with Israel by abusing the unity and eternity of the Jewish People. He speaks privately to one with whom there is deep love; so much so that, when he says, “I will worship” it is understood as “Let us worship idols” (see Rashi on Sanhedrin 61a and Minchat Chinuch, R. Yoseph ben Moshe Babad of Tarnopol, 1800-1874, § 462).

The meisit must be stopped before he succeeds in severing our ties with Hashem. Instead, the unity of Israel should become the foundation of Hashem’s glory.