If you were to enter a synagogue today, Chabad.org has a guide to what to expect. It includes: “You may also notice that many people are wearing white clothing, and some are even wearing a white robe called a kittel. This is because on Yom Kippur we are likened to angels. The angels do not eat, and neither do we. The angels devote themselves to praising G‑d, and so do we. The shroud-like kittel also reminds us that all life on earth comes to an end.”
Yom Kippur is the Day of Atonement. It’s history and significance is as follows (also from chabad.org):
“Forty days after they received the Torah at Mount Sinai and committed to be G‑d’s chosen people, the Children of Israel worshipped a Golden Calf. Moses pleaded with G‑d not to destroy His errant nation, and on the tenth of Tishrei G‑d said, “I have forgiven.” Ever since, we observe this date as the “Day of Atonement”—a celebration of our indestructible relationship with G‑d. It is the holiest day of the year, when we reconnect with our very essence, which remains faithful to G‑d regardless of our behavior.
“Yom Kippur is a fast day: from sundown on the eve of Yom Kippur until the following nightfall, we do not eat or drink. We also abstain from certain physical pleasures: wearing leather footwear, bathing or washing, applying lotions or creams, and marital relations. It is also a “day of rest,” on which all work is forbidden (as on Shabbat).
“The greater part of the day in the synagogue we engage in repentance and prayer. There are five prayer services: 1) The evening prayers, which begin with the solemn Kol Nidrei. 2) Morning prayer. 3) Musaf, which includes a description of the Yom Kippur Holy Temple service. 4) Afternoon prayer, during which the Book of Jonah is read. 5) Ne’ilah, recited as the day wanes and the verdict for the new year is sealed. The first four prayers include a (private) confession of sins to G‑d. Ne’ilah concludes with the congregation calling out the Shema in unison, and then a blast of the shofar signals the end of the day.
“Yom Kippur is followed by a festive meal. We rejoice, confident that G‑d has forgiven our sins.”
The author of the “New Testament” letter to the Hebrews wrote about the yearly sacrifice offered at the Temple to atone for the sins of the People of G-d.
For since the law has but a shadow of the good things to come instead of the true form of these realities, it can never, by the same sacrifices that are continually offered every year, make perfect those who draw near. Otherwise, would they not have ceased to be offered, since the worshipers, having once been cleansed, would no longer have any consciousness of sins? But in these sacrifices there is a reminder of sins every year. For it is impossible for the blood of bulls and goats to take away sins. Consequently, when Christ came into the world, he said, “Sacrifices and offerings you have not desired, but a body have you prepared for me; in burnt offerings and sin offerings you have taken no pleasure. Then I said, ‘Behold, I have come to do your will, O God, as it is written of me in the scroll of the book.'” When he said above, “You have neither desired nor taken pleasure in sacrifices and offerings and burnt offerings and sin offerings” (these are offered according to the law), then he added, “Behold, I have come to do your will.” He does away with the first in order to establish the second. And by that will we have been sanctified through the offering of the body of Jesus Christ once for all.
And every priest stands daily at his service, offering repeatedly the same sacrifices, which can never take away sins. But when Christ had offered for all time a single sacrifice for sins, he sat down at the right hand of God, waiting from that time until his enemies should be made a footstool for his feet. For by a single offering he has perfected for all time those who are being sanctified. And the Holy Spirit also bears witness to us; for after saying, “This is the covenant that I will make with them after those days, declares the Lord: I will put my laws on their hearts, and write them on their minds,” then he adds, “I will remember their sins and their lawless deeds no more.” Where there is forgiveness of these, there is no longer any offering for sin. Therefore, brothers, since we have confidence to enter the holy places by the blood of Jesus, by the new and living way that he opened for us through the curtain, that is, through his flesh, and since we have a great priest over the house of God, let us draw near with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water.
Lord Bless, Keep, Shine. . .