'Atonement' in the Bible

Now much time had been lost, and navigation was dangerous, because even [the time for] the fast (Day of Atonement) was already over, so Paul began to strongly warn them,

whom God displayed publicly [before the eyes of the world] as a [life-giving] sacrifice of atonement and reconciliation (propitiation) by His blood [to be received] through faith. This was to demonstrate His righteousness [which demands punishment for sin], because in His forbearance [His deliberate restraint] He passed over the sins previously committed [before Jesus’ crucifixion].

And such were some of you [before you believed]. But you were washed [by the atoning sacrifice of Christ], you were sanctified [set apart for God, and made holy], you were justified [declared free of guilt] in the name of the Lord Jesus Christ and in the [Holy] Spirit of our God [the source of the believer’s new life and changed behavior].

Therefore, it was essential that He had to be made like His brothers (mankind) in every respect, so that He might [by experience] become a merciful and faithful High Priest in things related to God, to make atonement (propitiation) for the people’s sins [thereby wiping away the sin, satisfying divine justice, and providing a way of reconciliation between God and mankind].