But You Are Not To Be Called "Rabbi"
From a literalist read of the Gospels, it appears that Jesus gives a clear prohibition against the use of religious titles, in particular, the title of "Rabbi".
A literalist read of the Gospels understands the following passage of Jesus as a prohibition against the use of religious titles, most often and in particular, the title of "Rabbi". In the Gospel of Matthew, we read:
“The scribes and the Pharisees sit on Moses’ seat, so do and observe whatever they tell you, but not the works they do. For they preach, but do not practice. They tie up heavy burdens, hard to bear, and lay them on people’s shoulders, but they themselves are not willing to move them with their finger. They do all their deeds to be seen by others. For they make their phylacteries broad and their fringes long, and they love the place of honor at feasts and the best seats in the synagogues and greetings in the marketplaces and being called rabbi by others. But you are not to be called rabbi, for you have one teacher, and you are all brothers. - Matthew 23:2-8
We will sidestep the traditional interpretation that this passage marks a departure from Judaism and instead look within the Rabbinic framework for a parallel.
Drawing distinction, Peter's protégé, Clement adds the caveat that Jesus particularly addresses "the hypocrites of them"¹ in this passage. If we search his words for a theme, it then becomes apparent that it is the behavior, not the title, that shapes the contours of the teaching. In a word, pride.
The issue here is that the character and behavior of these leaders are misaligned with their calling, and are lacking the pre-requisite trait of humility in their service of the Creator. Through their error, albeit a very human one, they inadvertently mislead others into similar outcomes.
Rabbi
As a Rabbi/teacher, Jesus is warning his students against the traps of leadership. While he is not dissuading them from leadership in general, he does refocus their aspirations to proper servanthood, warning that chasing titles, credentials, and public favor can create a recipe for disaster.
As we know too well, when someone becomes a leader of people, even with the purest of intentions, many hazards emerge that will test them. In time, the tendency to focus efforts toward that which is good for oneself alone. Often, the skills and conditions that elevate one to a spiritual leader are not the same one will need when leading others.
The following teaching, from the century before Jesus was born, is recorded in the Mishnah:
Shemaiah used to say: love work, hate acting
the superior, and do not attempt to draw near to the ruling authority. - Pirke Avot 1:10
In this passage, the word for "superior" is Rabbinate. The root of this word, Rav, (רב) is also the root of the words, "great" and "rabbi". Though Rabbi connotes master or teacher, in a literal sense, it means, "my great one". Embedded in the term is the hazard Jesus, and the Sages warn of - the potential that one may find themselves to be great.
This is not simply a Jewish problem though. Earlier in Matthew's Gospel, Jesus pointed out this trait among the Gentile leadership.
“You know that the rulers of the Gentiles lord it over them, and their great ones exercise authority over them. It shall not be so among you. But whoever would be great among you must be your servant, and whoever would be first among you must be your slave, even as the Son of Man came not to be served but to serve, and to give his life as a ransom for many.” - Matthew 20:25-28
Through this, we should recognize that pridefulness and ego are within the natural capacity of all people.
Interestingly, the word Reverand² carries a similar meaning to Rav or Rabbi, and even seems to bear a phonetic resemblance. In protestant Christianity, the title Pastor³ has been selected as it derives from the Latin word for Shepherd.
The word "Pastor", can be found to be a derivative of the Midrashic tradition where humility has been conjoined with shepherding. That is to say, a Good Shepherd is one who cares for their people like a flock. As many are aware, this idea is ubiquitous in modern Christianity today, though the origin of this imagery is Rabbinic⁴.
History has shown, no matter which title one chooses; Rabbi, Pastor, Priest, Reverand, Father, CEO, Manager, or Doctor - no title can innoculate a person from falling victim to their ego. Hashem should help us grow to become vigilant of our ego, guiding us to be humble, with the heart of a servant in all we do.
Notes:
¹ Clement Homilies - "Therefore He made use of this memorable expression, speaking the truth with respect to the hypocrites of them, not with respect to all. For to some He said that obedience was to be rendered, because they were entrusted with the chair of Moses. However, to the hypocrites he said, Woe to you, Scribes and Pharisees, hypocrites, for ye make clean the outside of the cup and the platter, but the inside is full of filth... - http://biblehub.com/library/unknown/the_clementine_homilies/chapter_xix_outward_and_inward_purity.htm
² Reverend: Early 15th century, also reverent, "worthy of deep respect, worthy to be revered" due to age, character, etc.
³ Pastor: The Greek word translated for "Pastors" is poimen, meaning Shepherds. ("Pastor" is the Latin word for shepherd.) - https://www.etymonline.com/word/Pastor
⁴ Midrashic example of Shepherd theme:
“Shepherd the flock of G_D that is among you, exercising oversight, not under compulsion, but willingly, as G_D would have you; not for shameful gain, but eagerly; not domineering over those in your charge, but being examples to the flock. And when the chief Shepherd appears, you will receive the unfading crown of glory. Likewise, you who are younger, be subject to the elders. Clothe yourselves, all of you, with humility toward one another, for ‘G_D opposes the proud but gives grace to the humble.’ Humble yourselves, therefore, under the mighty hand of G_D so that at the proper time he may exalt you. - 1 Peter 5:2–6
See:
... Our teachers have said: Once, while Moses our Teacher was tending [his father-in-law] Yitro’s sheep, one of the sheep ran away. Moses ran after it until it reached a small, shaded place. There, the lamb came across a pool and began to drink. As Moses approached the lamb, he said, “I did not know you ran away because you were thirsty. You are so exhausted!” He then put the lamb on his shoulders and carried him back. The Holy One said, “Since you tend the sheep of human beings with such overwhelming love - by your life, I swear you shall be the shepherd of My sheep, Israel.” - Exodus Rabbah 2:2