Here's the backstory:
* The Ritual: In the ancient Israelite tradition, on the Day of Atonement (Yom Kippur), the high priest would perform a ritual to atone for the sins of the people. Two goats were chosen, one for the Lord and one for Azazel (a figure associated with wilderness and the desert).
* The "Scapegoat": The goat designated for Azazel was symbolically loaded with the sins of the people. The high priest would lay his hands on its head, confessing the sins, and then send it into the wilderness. This goat was considered the "scapegoat," carrying away the sins of the people.
Therefore, the saying "scapegoat" is rooted in this biblical ritual and refers to someone who is unfairly blamed for the mistakes or wrongdoings of others.