Yehoash became the king in Jerusalem at the age of seven. Yehoyada, the Kohen Gadol, had led a successful coup against Athalya, the wicked queen who had murdered almost everyone in line to take over the kingdom. Only Yehoash survived, rescued as a baby by his aunt and hidden for six years. Now this child was being installed as the king in an attempt to restore order, sanity, and the Davidic dynasty. (See Melachim II Chapter 11.)
Not surprisingly, Yehoyada continued to be the main decision-maker before Yehoash came of age. He fulfilled this role with honor, guiding Yehoash in the ways of the Torah. Yehoash, in turn, faithfully followed the teachings of his righteous mentor.
ויעש יהואש הישר בעיני ה' כל ימיו אשר הורהו יהוידע הכהן
And Yehoash did what was right in the eyes of Hashem all the days that Yehoyada the Kohen instructed him. (12:3)
All the days of Yehoyada, but not after. Yehoyada died at the ripe old age of 130, and the situation deteriorated very quickly. The officers of the king deified him, and he went along with it. Idolatry once again became rampant in the kingdom. Hashem sent prophets to urge the people to repent, but the people ignored them.
Hashem then sent Zecharya, the son of Yehoyada, to admonish the people for abandoning Hashem. In one of the most tragic events in history, the people conspired against Zecharya the prophet and stoned him to death inside the Beis Hamikdash. Yehoash repaid his debt to Yehoyada for overthrowing Athalya, protecting him as a baby, installing him as king, and mentoring him by murdering his son.
The following year Jerusalem was overrun and plundered by a tiny army from Aram, the king's officers were killed, and Yehoash himself was badly hurt. His own servants killed him on his bed in vengeance for his treachery against Yehoyada's children, and he was buried outside the royal cemetery. (See Divrei Hayamim II Chapter 24.)
The blood of Zecharya boiled where it had been spilled until the Beis Hamikdash was destroyed. It did not settle until approximately three million Jews were murdered by Nevuzaradan, the Babylonian general who conquered Jerusalem and helpfully sought to appease the blood. (See Gittin 57B.)
(In a bizarre twist, Nevuzaradan then had a sobering realization. If so much tragedy had befallen the Jews for murdering one person, what would happen to him? He fled his army, sent a letter home, and converted.)
How did Yehoash turn so bad so quickly after the death of his mentor? He did not experience a slow deterioration, as one might have expected; he fell off a spiritual cliff after behaving with great righteousness all his days until that point.
The Malbim on Melachim II 12:3 offers a deep insight. The navi writes that Yehoash did what was right in Hashem's eyes all the days that Yehoyada instructed him. There is a difference between instruction (הוראה, hora'ah, similar to Torah) and teaching (לימוד, limud).
According to the Malbim, Yehoyada made a subtle but critical mistake, which is indicated by the wording of the pasuk. He instructed Yehoyada what to do, but he didn't teach him in the ways of learning, to be able to determine the proper path with his own mind. Once Yehoyada died, Yehoash lacked the tools to continue on the righteous path, and he was quickly led astray – to the very depths of idolatry and treachery.
Nowadays this same critical mistake has become the norm. Many people believe that the path of Torah is to outsource one's mind to a religious figure and then blindly follow instructions. The individual is conveniently free from having to engage in critical thinking and intellectual struggles, and absolved of responsibility for wrongdoing. The obligation to abide by the rulings of rabbinic authorities – which is real, but itself limited in Jewish law – has been corrupted into a supposedly Torah-sanctioned version of “just following orders”.
Even if one is fortunate to outsource his mind to a pious scholar like Yehoyada, this is not the way to follow the Torah and serve Hashem. It is only a matter of time before things fall apart. Even pious scholars are not infallible, they are not always accessible, and they do not live forever. No matter what, a person cannot become close to Hashem if he mindlessly follows orders like a monkey, even if all the orders are proper.
Normalizing blind obedience to religious authorities also creates a situation that is ripe for corruption. The “elite class” can easily be overtaken by phonies who put on a show of piety while misleading their mindless followers, who dare not question them. Once that happens, the greatest acts of idolatry and treachery can be sold to the public as the ways of the Torah.
It's really that easy.
A rabbi must not merely instruct the people, but teach them. He must help them develop the tools to learn correctly and determine the proper path with their own mind.
Unlike a cult leader, a rabbi gently weans his students off their dependence on him so they can function on their own. His continued mentorship should be a luxury, not a necessity. He nurtures as many people as possible to grow into his job when the time inevitably comes.
Is your rabbi teaching you, or just yelling out instructions and rhetoric?
Millions of Jews eventually lost their lives because Yehoash was spiritually helpless without Yehoyada holding his hand. Millions more are in peril today unless they stop mindlessly taking instructions, and start to truly learn.