CCC 2091
Life in Christ›SECTION TWO THE TEN COMMANDMENTS›CHAPTER ONE YOU SHALL LOVE THE LORD YOUR GOD WITH ALL YOUR HEART, AND WITH ALL YOUR SOUL, AND WITH ALL YOUR MIND›I. "You Shall Worship the Lord Your God and Him Only Shall You Serve"
The first commandment is also concerned with sins against hope, namely, despair and presumption: By despair, man ceases to hope for his personal salvation from God, for help in attaining it or for the forgiveness of his sins. Despair is contrary to God's goodness, to his justice - for the Lord is faithful to his promises - and to his mercy.