God remembered his people, who were slaves in Egypt, and had delivered them out of bondage with a mighty hand. Once he delivered them, God spoke again to ensure that they lived in the light of this freedom. God graciously speaks to them from Mt. Sinai, assuring his people of his covenant love for them and exhorts them to respond to his saving activity by joyfully living under his good rule.
As Christians we are called to do the same: In the light of what God has already done in Jesus to save us from our sin, we are now to respond in trust and full obedience to God.