§2086
Morals › … › I. "You Shall Worship the Lord Your God and Him Only Shall You Serve"
"The first commandment embraces faith, hope, and charity. When we say 'God' we confess a constant, unchangeable being, always the same, faithful and just, without any evil. It follows that we must necessarily accept his words and have complete faith in him and acknowledge his authority. He is almighty, merciful, and infinitely beneficent. Who could not place all hope in him? Who could not love him when contemplating the treasures of goodness and love he has poured out on us? Hence the formula God employs in the Scripture at the beginning and end of his commandments: 'I am the LORD.'"
Source: Catechism of the Catholic Church (Vatican.va)