“The reference to the Passover was probably suggested by the season of the year, and was very apropos. Leaven is a type of evil, illustrating the hidden constant way in which it spreads. To the Jew it was a symbol of the corruption of Egypt, and was directed just before the Passover to search diligently in every part of his house, and remove it. [Ex. 12:15] But to the Christian Christ is a perpetual sacrifice, an ever-present paschal Lamb, demanding and enforcing constant vigilance and unceasing cleanliness. The individual must put away every sinful habit of the old life. The church must purge itself of all whose lives are sources of corruption.”
None of these sacrifices possessed any intrinsic value sufficient to free the conscience of the sinner from the pollution of guilt, or to obtain his pardon from God; but they gave a formal deliverance from a secular penalty and they were figurative representations of the full and perfect sin offering which was to be made by Christ.
(uh tohne' mehnt), meaning reconciliation, was associated with sacrificial offerings to remove the effects of sin and in the New Testament,] refers specifically to the reconciliation between God and humanity effected by the death, burial, and resurrection of Christ. Old Testament Primarily in the Old Testament, atonement refers to the process God established whereby humans could make an offering to God to restore fellowship with God. Such offerings, including both live and dead animals, incense, and money, were required to remove the bad effects of human sin.
The only fast day stipulated in the Mosaic law was the annual day of Atonement (Yom Kippur), observed on the tenth day of Tishri (September-October) at the conclusion of ten days of penitence. The day of Atonement was the only day of the year that the priest entered the holy of holies to make sin offerings for himself, his family, and the “assembly of Israel.” After making these offerings, the nation's sins were symbolically laid on the scapegoat “Azazel” that was released into the wilderness to die.”
Atone=kapar, "to cover over, atone, propitiate, pacify.Most uses of the word, however involve the theological meaning of "covering over," often with the blood of a sacrifice, in order to atone for some sin. It is not clear whether this means that the "covering over" hides the sin from God's sight or implies that the sin is wiped away in the process.