The essence of Yom Kippur atones for those who repent, as it says (Vayikra 16:30), כִּי בַיּוֹם הַזֶּה יְכַפֵּר עֲלֵיכֶם לְטַהֵר אֶתְכֶם מִכֹּל חַטֹּאתֵיכֶם לִפְנֵי ה’ תִּטְהָרוּ - For on this day He shall provide atonement for you (Rambam, Hilchos Teshuvah 1:3).
Chazal (Shavuos 13b) on this issue: According to Rav, “the essence of the day atones” even for those who do not repent, while Rabbanan hold that it atones only for those who repent. The Rambam rules like Rabbanan, that the day atones only for penitents, as explained by the Kesef Mishneh.
The commentators explain that even though the Rambam rules according to Rabbanan, he uses the language of Rav: “The essence of the day atones.” Because although the Rabbanan, whose opinion is accepted, require repentance for the atonement of Yom Kippur, and “the essence of the day” without repentance does not suffice, the primary atonement of Yom Kippur, according to all opinions, stems from the power of the day itself. However, the Rabbanan maintain that the essence of the day is ineffective for those who do not repent.
The rationale behind this is due to the unique nature of Yom Kippur, which is a day fundamentally different from all others. As stated in Tanna D‘vei Eliyahu Rabbah (chapter 1): )ולא( וְלוֹ אֶחָד בָּהֶםיָמִים יֻצָּרוּ - The days were fashioned, and for Him, one among them (Tehillim 139:16)—this refers to Yom Kippur for Yisrael, which is a day of great joy before the One who spoke and the world came into being, given with great love to Yisrael.” Similarly, in Otzar Midrashim, Midrash Chaser Veyaser (p. 197), it states: The days were fashioned, and not one among them. It is written ולא and not with an aleph, but we read it as וְלוֹ - for Him with a vav, teaching that Hakadosh Baruch Hu created one unique day from all others [that is different and not among the others]—Yom Kippur, for atonement.”
This midrash explains that Yom Kippur is fundamentally distinct in its very creation from all other days. While the days were fashioned according to one type of creation, Yom Kippur was created uniquely, endowed with a sublime spiritual nature. It is a day entirely spiritual, unlike other days, which are primarily physical. Yom Kippur emanates purity and holiness from the upper spiritual realms. Thus, on this day, we are likened to the ministering angels: we do not eat or drink like them, we dress in white like them, and we recite “Blessed is the Name of His glorious kingdom” aloud, as they do.
This is the meaning of “the essence of the day atones”—through the immense sanctity and wondrous light that shines on this day, purifying the souls of Yisrael. It is of this unique light that we say on the night of Kol Nidrei: אוֹר זָרֻעַ לַצַּדִּיק - Light is sown for the righteous (Tehillim 97:11), as is known. The day itself, through its sanctity and purity, cleanses the sins of Yisrael.
However, according to the halachah, as established by the Rabbanan, there is a condition for the atoning effect of the essence of the day: repentance. If one repents, the day automatically atones. Nevertheless, even according to the Rabbanan, the erasure of sins on Yom Kippur is not primarily achieved through the individual‘s acts of repentance, as on other days of the year, but rather through the power of the day itself, as derived from the pasuk , כִּי בַיּוֹם הַזֶּה יְכַפֵּר עֲלֵיכֶם - For on this day He shall atone. The day itself is the agent of atonement.
As demonstrated in the discussion of the four types of atonement (Yoma 86a), Yom Kippur can atone even for transgressions that ordinary repentance cannot remove. Repentance is needed, however, to enable the atonement of the day to take effect. If a person clings to their sins and refuses to repent, they block the atonement of the day from penetrating and cleansing their soul of its impurities.
Thus, the pasuk continues: For on this day He shall atone—but this is contingent upon to purify you. You must abandon sin and return with repentance to Hashem on Yom Kippur. Then the essence of the day will atone for you, purifying you, as the pasuk concludes, לִ פְ נֵי ה ‘ תִּטְהָרוּ - Before Hashem, you shall be purified.
It is said of Rav Yosef Chaim Sonnenfeld zt”l, the revered Rav of Yerushalayim, that after the passing of the chazzan who led the Yamim Nora’im tefillos in his shul, the question arose during Elul as to who would take his place. The deceased chazzan‘s son was in mourning and had not yet established a tradition of leading prayers during the Yamim Nora’im, and the poskim write that a mourner in such a situation should not lead the prayers.
