Righteous Life Ministry
In the Old Testament, God showed Abraham to sacrifice a pristine animal such as a lamb or goat for the redemption of sin. Actually this goes further back to the Garden of Eden where Adam and Eve sinned by disobeying God and ate from the tree of the Knowledge of Good and Evil. God killed some animals and used the skins for clothing for Adam and Eve before expelling them from the Garden of Eden.
The Jewish people continued this tradition of annual sacrifices for the atonement of sins until the destruction of the temple in Jerusalem. This covers over the sin but it is not eliminated. This practice recently restarted again.
Jesus was born of a virgin to die on the cross. He volunteered to do this for all people to be our purest sacrifice. While on the cross, Jesus took on all sin or everyone who becomes born again. By becoming born again; our sin is totally eliminated in a process called remission of sin. The sin is totally done away with as if it never happened. Jesus died for His people while other religious systems you generally have to die for the person who starts it.
For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved. He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God. (John 3:16-18)