Expiation
Expiation names the act of covering or wiping away sin so that fellowship with God is restored — the reconciling work scripture treats under the broader category of atonement. In the Mosaic system this took the form of animal sacrifice, the Day of Atonement, and ritual cleansings; in the new covenant it centers on the once-for-all death of Jesus.
Click here to read the full topic on this subject: Atonement