Our reading tonight is Exodus 19 and 20:1-17.
I never saw the giving of the Ten Commandments as part of God offering a covenant to his people.
Ultimately, without the Ten Commandments we have no standard by which to measure our lives by. Therefore we will never see a need for a Savior. But the Ten Commandments say so much more than just what they "say". They show us our sin, our need for redemption, and God's holiness. They extend to all of the commands in the New Testament as well.
This is a great way to use the "law" in evangelism.