There’s an interesting difference between the Old Testament and New Testament as far as the word “atonement.” Under the old covenant, the Hebrew word means “covering” and was specifically associated with the covering or lid of the ark of the covenant. Inside the ark was the Law and to cover it (make atonement), allowed God to “pass over” the sins of the people. Ps 32:1 “How blessed is he whose transgression is forgiven, whose sin is covered.”
“Atonement” in the new covenant comes from a Greek word that does not mean “covering.” Unfortunately, some modern translations suggest this translation of the word. It literally means “reconciliation” and implies that sin was not merely covered, but removed. “He has been manifested to put away sin by the sacrifice of Himself” (Hebrew 9:26). The blood of animals only covered sin, the blood of Jesus removed sin.
Just like cleaning your house, there’s a big difference between covering the mess and cleaning up the mess.Before Jesus, sin was covered. When He died and came back from the dead, sin was removed “as far as the east is from the west” (Psalm 103:12).