The Day of Atonement

The Jewish Calendar
The calendar used by most of the world is the Gregorian calendar, introduced in 1582 by Pope Gregory XIII. The Jewish calendar, which is the official calendar in Israel and the religious calendar for Jews everywhere, was instituted by Hillel II around the year 359. Whereas the Gregorian calendar is based on the sun, the Jewish calendar is based on both the sun and the moon. Years coincide with the sun, and months coincide with the moon. For more information, see Judaism 101: Jewish Calendar and Calendars Through the Ages: The Jewish calendar.

As the Day of Atonement, Yom Kippur recalls the story of when Moses came down from Mt. Sinai to find Aaron and the Israelites making merry and worshipping the golden calf. Moses was furious that instead of praising God, his people were glorifying an idol. In the heat of anger, he hurled the Ten Commandments to the ground, breaking the tablets. Moses went back to Mt. Sinai seeking God's forgiveness for the Israelites' folly and requested another set of tablets. God forgave the sins of the people and, with a new set of tablets in hand, Moses returned to the Israelites on the 10th of Tishri with this to say:

And this shall be an eternal law for you. Each year on the tenth day of the seventh month you must fast and do no work. This is true of the native born and of the convert to Judaism who comes to join you. This is because on this day you shall have all your sins atoned, so that you will be cleansed. Before God you will be cleansed of your sins. It is a Sabbath of Sabbaths to you, and a day upon which you must fast. This is a law for all time. (Leviticus 16:29-31)

A Jew's life depends on whether or not he or she makes the decision to make amends during the High Holiday period through the means of teshuvah (repentance), tzedakah (charity), and tfiloh (prayer).