When was the Day of Atonement first begun?
The Day of Atonement was first begun shortly after the Israelites came out of Egypt, along with all the other Feast Days such as Passover, First Fruits, and Unleavened Bread. It was a Fall feast, later known in English as Yom Kippur, and is recorded in Leviticus chapter 16.
Les teaches that the Day of Atonement began back in the days shortly after Israel came out of Egypt, the same as all the other Feast Days—Passover, First Fruits, Unleavened Bread, and the rest. He notes that Passover was the Spring feast, a memorial of the night in Egypt when the death angel flew over and the people were protected by the blood. Atonement, however, was in the Fall, and its present English name is Yom Kippur. Les explains that Yom Kippur is a far better definition or explanation than "Atonement," because in Leviticus the word "Atonement" is really a misnomer. He suggests the English translators should not have called it the Day of Atonement, since there was no Atonement—animal bloods could not take away sin, which is what Atonement speaks of. He points out that the word can be split into "At-one-ment," which is a good definition.