"There is no man on earth of such righteousness that does good and is free from sin" (Kohelet 7:20). Being human means to sin, and since G-d created us as humans, this cannot be all bad. We all know that a person can grow only by learning from their mistakes. And the greater the person, the greater the mistakes. 

"When, asher, a leader sins" (Vayikra 4:22). Based on a play of the words asher, when, and ashrei, blessed, our Sages, quoted by Rashi, comment that, “Blessed is the generation in which the leaders atone even for their inadvertent sins; how much more so, for their willful sins”. The question is not whether our leaders will sin—that is a given—but rather, what will they do after they sin. 

If one avoids making difficult decisions, if one is not involved in determining community priorities, one avoids many a sin. But that is not the way of leaders or leadership. Difficult choices must be made, and thus mistakes will be made, mistakes that we can all learn from. 

Rashi assumes that our leaders will sin not only inadvertently, but willfully. This, too, is part of being human. This is fine, provided we grow from our missteps and, as Rashi notes, are not afraid to admit them. The greater the leader, the harder it is to admit mistakes. Might not such an admission diminish them in the eyes of their followers? While this, too, is part of human nature, the Torah teaches that revealing one's humanity is ultimately the more effective approach. 

"The people gathered, vayikahel, around Aharon" (Shemot 32:1); and soon afterward, they committed the sin of the golden calf. While G-d expects us to sin, and perhaps even desires it to some extent, there are some sins that are so great that the opportunity for repentance is not possible. While one may truly and sincerely regret one's actions, the impact is so great that punishment must be one's fate. Learning from our mistakes will have to come later, and in changed circumstances. The sin of adultery, for example, is so severe that amends are often not possible. At times, even if the couple agrees to forgive and forget, they may not remain married and divorce is forced upon them. Any lessons to be learnt will have to be applied to their next marriage. 

Such would appear to be the sin of the golden calf. When the Jewish people rejected the G-d of history, the G-d of revelation, the only apparent option was for G-d to destroy them. “Now, let Me be, that My anger may blaze forth against them and that I may destroy them and make of you a great nation” (Shemot 32:10). 

Yet soon afterwards, we read, "Vayakhel Moshe, Moshe assembled the entire community and said to them: These are the words that G-d has commanded for you" (Shemot 35:1). G-d's readiness to accept genuine teshuva is much greater than we could have imagined. Even after such a heinous act, G-d was ready to re-establish a bond, possibly even a stronger bond, with the former sinners. The same nation that gathered, vayekahel, together to build the golden calf now gathers, vayakhel [1], to re-establish their bond with G-d. To attest to that ongoing relationship even after such a terrible sin, the Torah repeats the long and detailed instructions of the construction of the Mishkan, the symbol of that relationship. 

In restating the command to build the Mishkan, the Torah begins with the laws of Shabbat, laws we have seen many times before. While our Sages derive from these verses that construction of the Mishkan was to be halted for Shabbat (Rashi, 35:2), it seems that there is an additional reason that Shabbat is mentioned here. Shabbat it is the antidote to idolatry. It is Shabbat that testifies to our belief in G-d as the Creator, so much so that our Sages equate the violation of Shabbat with idolatry[2]. After the sin of the golden calf, the path to the Mishkan must begin with Shabbat.  Only after we demonstrate our acceptance of G-d can we build a home in which for Him to dwell.

[1] With no vowels in the Torah, it is the same Hebrew word, vykhl, both in regards to the sin of the golden calf and that of building the Mishkan

[2] Modern-day authorities have noted that this equation is no longer valid, as many who violate Shabbat demonstrate in other ways their belief in G-d. Fifteen hundred years ago, those who violated Shabbat did so as a way to demonstrate that they did not believe in G-d.