In the history of salvation God was not content to deliver Israel "out of the house of bondage" by bringing them out of Egypt. He also saves them from their sin. Because sin is always an offence against God, only he can forgive it. For this reason Israel, becoming more and more aware of the universality of sin, will no longer be able to seek salvation except by invoking the name of the Redeemer God.
Source: Catechism of the Catholic Church (Vatican.va)