Does one have to be Jewish to be a rabbi

Question

In terms of what we call semicha today, does one have to be Jewish to receive or hold it? Is it simply an indicator of learning (like an academic degree) which could be reached by anyone?

Knowing that many semicha conferring programs won't accept a non-Jew, I suggest the following hypothetical:

Someone raised a religious ("Orthodox") Jew studies for and is granted semicha. He writes, learns, answers practical questions based on his learning and "is" a rabbi. Ten years later, after some digging by members of his family, he discovers that his maternal great-grandmother was not Jewish. Therefore, he was never Jewish.

During the time that he practiced as a rabbi, was he one? The learning was the same as was his personal piety (if that matters). If someone asked him for an answer on a situation and was bound (at the time) by his answer as we do not shop for answers, is that person still bound after the heritage is discovered?

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[I wonder if I asked a local smart Jewish person a question and he gave me an answer, whether I would be bound by his words even without semicha as I chose him as my generic expert...separate question]

Answer 1

לִכְאוֹרָה it is a machlokes:

The Mordechai and Radvaz held that if a kehillah held a minhag that was k’neged halacha, there is room to say that we do not abrogate that minhag.

However, the Pri Chadash and possibly Rav Elyashiv argued that, in general, we abolish such a minhag.

Answer 2

OK, I just hate to leave interesting questions unanswered:

You ask several different questions I will address one by one:

1. To your title question: Yes, one has to be Jewish to be a counseling Rabbi. Here's why, but first, I'd like to define who's a Rabbi.

There are two usages of this word: 1. a respectful and knowledgeable Jew (sometimes I'm called a Rabbi :) 2. one who is authorized and certified to JUDGE (as you referred to סמיכה - which has a permit to judge).

In other words, when one comes to a Rabbi, the latter can be either a non-obligating source of wisdom (just as Google or MI@stack) or be the Posek for the asker as if there was a Rabbinical court of one.

In the first case, as I said, anyone can be Rabbi, including a woman or a computer. In the second case, only a Jewish adult male can be a Dayan (see Rambam's Hilchot Sanhedrin or Shu"A Ch"M). Case closed.

2. To the body of your question - can someone lose his Jewishness?

No, after there's a Chazoke (חזקה) that someone is a Jew, only an accepted Jewish Rabbinical court can theoretically change that. In other words, if one who's been a pious Orthodox Jew for decades finds out some information that undermines his Jewishness he does not become a non-Jew until explicitly decided by a court. Because in the Rabbinical court NOTHING (no piece of evidence, as you put it "he discovers) matters but two Kosher witnesses, it is practically impossible to get anybody out of the Chazoke of his Jewishness.

So your conclusion "he was never Jewish" is totally wrong, and no matter what he will continue to be Jewish.

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BTW try to find anything that really proves that his grandmother was not Jewish. What could it be? Besides two Kosher witnesses (that might not be accepted by the court also) there's nothing a Beis Din can not reject.