It is said that on Yom Kippur, the Jewish people are elevated to the level of angels. We do not eat or drink, we wear white as a sign of purity, and we spend the day immersed in prayer.
The Rabbis noted that the numerical value of the word, השטן, “the Satan,” is equal to 364. It is a hint that Satan, or the Yeitzer Hara, evil inclination, has power over us for all of the days of the year, but one.
On Yom Kippur, Hashem tells Satan to report to him as to what His people are doing. When he describes how the sanctity of this day is treated, there is the realization that just as angels cannot be harmed by Satan, Am Yisrael receive equal protection.
This is also the reason why the phrase after the first line of Shema, is said loudly. The angels praise G-d daily with the words, ברוך שם כבוד מלכותו לעולם ועד. The Shulchan Aruch explains that we say this verse softly, all year round, so as not to insult the angels.
But on Yom Kippur, they are not insulted as we are on the level of angels on that day. We also have the right to recite this verse out loud, just as they do.
It is obvious that we are not automatically elevated to such a high level. If we apply ourselves with the proper preparation, and fulfill the obligations of the day, only then will we receive Divine protection, and spiritual elevation,