In more recent times, I see more and more Christians claiming that not only was Jesus a learned scholar, but he was actually a rabbi. This is evidenced, in their view, from the fact that he's called "rabbi" by some in the NT.
In Judaism, though, this is not a feasible view. Not because there's no such thing as a heretical rabbi - there were, unfortunately - but because becoming a rabbi in Talmudic times (when Jesus lived and certainly when the authors of the NT lived) was not quite as simple as receiving ordination from one's own rabbi (which isn't a simple process in itself) and having a shiny rabbinical degree to hang up on the wall. During those times there was something called "Smicha". This is short for "Smichat Yada'im" and refers to a special process of ordination which included at least three ordained rabbis laying their hands upon the head of the rabbi-to-be and passing on the traditional ordination of Jewish authority passed down from generation to generation in an unbroken chain, all the way back to Moshe. According to tradition, after the time of Rabbi Yehudah the Prince, the special form of Smicha was canceled and what has since been called rabbinic ordination, also referred to as "Smicha" is not the same process and this has halachic (Jewish law) ramifications to this day. I will not get into all of the fine points about Smicha here. Suffice it to say that the ancient Smicha had more authority than the one we have today and in ancient times, a distinction was made between those sages who had Smicha and those who didn't.
Indeed, there were Talmudic sages who didn't receive Smicha and as such, were not called "rabbi" (I'm not including sages like Hillel and Shammai who as prince and head of the court respectively, of course had ordination but were not called "rabbi" for other reasons), such as Shimon ben Azai, Shimon ben Zoma, Shmuel and so forth. The Talmud is not lacking in descriptions of the greatness of these individuals, but they simply didn't qualify for Smicha, for different reasons. Eventually a new rabbinical status quo was established and sages, upon receiving the lesser Smicha, got the title "rabbi" but again, a distinction was made between the rabbis of the superior Smicha and those of the lesser.
Now, about Jesus: We can agree that we don't know too much about Jesus. The NT's version of the story doesn't provide us with details about who taught Jesus. There's nary a rabbi in sight in the NT to offer any form of support for the man, save, perhaps, for Nicodemus, who no one knows who he was, as he's not mentioned anywhere else, at least not by that name.
It's possible that Jesus was an autodidact. This may explain the various rulings he made on his own account, that don't quite match rulings of contemporary authorities; he may have thought that as a kind of "freelance scholar" he could do what he wished. It's also possible that he was taught by someone, but it is, in my opinion, quite telling, that this mysterious teacher is never named.
According to some views, there are hints in the NT that Jesus didn't really know what he was talking about when he was talking about Judaism.
And of course, we can't forget about the Temple incident, in which Jesus went full-on vigilante, causing havoc around the holiest place of the Jewish people and demanding punishment without following the proper official halachic court proceedings.
Due to all of which I've written so far, it seems highly unlikely that Jesus was ever actually an ordained rabbi: Who was his rabbi? Who would have given him Smicha? How did all of these sages miss out on all of his "quirks"? Why would they even consider giving such a person Smicha?
The Talmud tells us of a man usually called "Acher" - "other", a former sage named Elisha ben Avuyah. He was a great scholar until he fell and turned to Hellenism and then proceeded to do his best to convince other scholars to leave Judaism. Yet, he's mentioned as a sage in the Talmud. The Talmud isn't known for hiding away the sins, mistakes and downfalls of the sages, knowing that there's wisdom to gleaned from these events. Jesus is also mentioned in the Talmud, but not as a sage. At best, he might have been a student of Yehoshua ben Perachyah, but even that is a matter of debate. Were Jesus to have been a sage who had fallen off the path of Judaism, it does not seem to make sense that the Talmud would hide this fact from its historical notes.
Therefore, it seems much more likely that he had never been an actual rabbinical sage to begin with. More likely, either he was self-taught or he had a teacher that was also not a rabbinical sage. But a true, ordained rabbi Jesus likely was not.
So why was Jesus called rabbi in the NT? The most likely reason, in my view, is that "rabbi" means "master" and it was also a term that was becoming more common at the time for revered individuals. Revering their teacher, the disciples, who it seems were not too learned, chose the popular title without really understanding what it truly meant in Judaic terms, past basic Aramaic vocabulary skills.
