As Maimonides writes: (Commentary on the Mishnah, Tractate Sanhedrin, Chapter 10, introduction to Mishnah 1)
The principles of our religion and its foundations are thirteen foundations. The First Foundation is that the Creator, blessed is His Name, creates and directs all created beings, and that He alone made, makes, and will make everything (as above).
. . .
The Thirteenth Foundation [is] resurrection of the dead which we already explained . . .
and —
When a person believes in all these principles, and his or her faith is clear concerning them, then they join the community of Israel. Then the individuals of the community must love them, have mercy upon them, and conduct themselves in every way that the Almighty commanded us concerning the treatment of our fellow Israelites one to another, with the fullest love and fellowship.
Even if this person should ever transgress
However, if a person disregards any of the Thirteen Principles, he leaves
the community because he is a heretic. Then the community must hate him and
destroy him. When King David said, "I hate those who hate You, O
This has been a lengthy digression within my explanation of the Mishnah. However, I have done so because I have seen its benefit for faith, since I assembled the beneficial content from the classics of our faith.
Know these principles! Learn them well! Go over them often, and meditate well upon them!
If you should think that you have mastered these principles after going
over them a handful of times,
Now it is up to the Almighty to sustain me and lead me along the Good Way.
— Maimonides, in concluding the Thirteen Foundations of Faith
Freely translated by Nathaniel Segal from:• Maimonides' Commentary on the Mishnah (an elucidation).
Tractate Sanhedrin, Chapter 10, introduction to Mishnah 1.
(Babylonian Talmud. Vilna, Lithuania: The Widow and the Brothers Romm Publishing,1860-1886 ,pp. 247-8.)
his or her faith is clear concerning all these principles - Their actions validate their faith.
then they join the community of Israel; he leaves the community because he is a heretic - A community of Jews is supposed to be safe for Jews to observe the Covenant. This is what Maimonides refers to when he writes about ". . . a person [who] believes in all these principles, and his or her faith is clear concerning them . . ." We members of the community can generally trust this person despite their shortcomings – "the inferiority of his nature overpowering him," and so on. They try to validate their faith in their actions.
A heretic stands at the other extreme. They are not just a bad influence within our community. They pose an ongoing threat and an existential threat. Their bad influence is against the Covenant itself. But, the Covenant is the only reason for the community to exist.
Rulings over the generations seem to me to be consistent: there are no heretics today who warrant expulsion from the community and destruction. Maimonides shows this himself by never condoning expulsion of any Jew who converted to Islam without obvious conviction. This is true even more so when the Jew was "strongly encouraged" to convert to Islam. A Jew reciting the Muslim Shahada in public – "There is no god but the One and only
Even concerning the heretical Jewish sect of Karaites who had a sizable membership where Maimonides lived (the environs of Cairo, Egypt), Maimonides didn't suggest that they be forced to live outside the Jewish community and be destroyed if possible.
What I've written is simplistic in the extreme. A reliable source (Rabbi Aharon Soloveitchik) discusses these issues by ranging through related Talmudic discussions, through extensive commentaries on the Talmud, and through Maimonides himself as he rules in his Code. These are scattered but related rulings. When assembled as a whole, the pattern emerges as I've tried to represent it.
Sefer Parach Mateh Aharon by the Rosh Yeshivah of Brisk in Chicago, Rabbi Aharon Soloveitchik, of blessed memory. (Israel: Targum Publishing, 1997)
. . . the coming of the Messiah. Even though he
Maimonides' Commentary on the Mishnah - introduction to the first Mishnah in this chapter
Hebrew, the traditional translation from Arabic
(Babylonian Talmud. Vilna, Lithuania: The Widow and the Brothers Romm Publishing,1880-1886. pp. 247-8.)