Belief and Ancestry

I was puzzled for a long time over a passage in the Rambam's Iggeres Teiman. He writes (Kafach edition, p. 27) that anyone whose ancestors stood at Mt. Sinai will never dispute Moshe's prophecy, since it says (Ex. 19:9), "And they will believe in you forever". However, there have been siblings and children of famous rabbis who have become disbelievers. Does that put the ancestry of famous rabbis into question?

I saw an interesting answer to this given by R. Yitzchak Sorotzkin in his Rinas Yitzchak (Num. 16:28). He quotes the Brisker Rav as saying that Korach and his men deviated from two of the thirteen fundamental principles of Jewish faith: they rejected that Torah was from heaven (principle 8) and the veracity and uniqueness of Moshe's prophecy (principle 7).

Click here to read moreWith this, the Brisker Rav explained the repetition in Num. 16:28: "And Moses said: 'By this you shall know that 1) the Lord has sent me to do all these works, 2) for I have not done them of my own will.'" The first phrase refers to Moshe receiving prophecy and the second phrase to the Torah being from God and not Moshe's creation.

However, if Korach and his men really did reject these principles, how can the Rambam state that anyone who was at Mt. Sinai will never reject them? Korach and his men were at Mt. Sinai!

R. Sorotzkin suggests that the Rambam was only referring to someone rejecting Moshe's prophecy. Someone who accepts that Torah is from heaven will never reject the unique prophecy of Moshe (and claim that we received the Torah some other way). The descendants of those who were at Mt. Sinai who continue to believe that the Torah was given there, will always treasure the unique role of Moshe in the transmission of the Torah.

Korach and his men rejected the divine origin of the Torah and therefore their additional rejection of Moshe does not contradict the Rambam's claim. The same can be said for those unbelieving Jews who reject that the Torah is from heaven. Even according to the Rambam, their disbelief does not imply that their ancestors were not at Mt. Sinai. (Note, however, that the phrasing of the Midrash Ha-Gadol on that verse does not allow for this interpretation.)