As is often the case, research increases the volume of questions without necessarily leading to a simple or understandable answer. That was certainly the case this time. I found the word “atonement” is very prominent in the Jewish faith (Yom Kippur is the Day of Atonement) and in the Church of the Latter Day Saints of Jesus Christ. Although it may, perhaps, be seen as less prominent in other religious traditions, it is central to the Christian faith.
Atonement originally meant “at one ment:” “at one,” or in harmony, with someone. It describes the saving work that God did through Jesus to reconcile the world to God, and also the state of a person having been reconciled to God. Throughout history, Christians have used different metaphors and have given differing explanations of atonement to express how it might work. Even though faiths and denominations differ in their understanding, Christians emphasize that Jesus is the Savior of the world and that through his death the sins of humankind have been forgiven.
To atone means to make amends: to repair a wrong done. Biblically, it means to remove the guilt of men and women. Old Testament atonements offered by the high priest were temporary and a foreshadowing of the real and final atonement made by Jesus. Jesus atoned for the sins of the world. This atonement is received by faith, and because of it, fellowship with God is restored.
There is so much more information and historical narrative available; I urge you to delve into it. You’ll find an amazing adventure that has resulted in events like the building of cathedrals and the Crusades of the Middle Ages!