CCC 2084 God makes himself known by recalling his all-powerful loving, and liberating action in the history of the one he addresses: “I brought you out of the land of Egypt, out of the house of bondage.” The first word contains the first commandment of the Law: “You shall fear the LORD your God; you shall serve him. .. You shall not go after other gods.”1 God’s first call and just demand is that man accept him and worship him.
1 Deut 6:13-14.