Many people are under the misconception that starting in Exo.19:5-6, a new system of salvation was set up, faith+works.
Nothing in those verses say any such thing.
What was set up was a system by which the Jewish people were to live, to show the world they were a unique People.
They were to be a Priest People, to reach the world with the truth about the Living God.
The Law was about the WALK (Exo.18:20) not about salvation, since no man born with a sin nature, could keep the Law.