Act of Faith
Actus Fidei
The traditional Act of Faith — the catechism prayer professing belief in God and all His Church teaches, prayed for centuries at morning and night.
O my God, I firmly believe that Thou art one God in three Divine Persons, Father, Son, and Holy Ghost; I believe that Thy Divine Son became man and died for our sins, and that He will come to judge the living and the dead. I believe these and all the truths which the Holy Catholic Church teaches, because Thou hast revealed them, who canst neither deceive nor be deceived. Amen.
History
The three Acts — of Faith, Hope, and Charity — entered common Catholic life through the catechisms of the seventeenth and eighteenth centuries, and generations of Catholics learned them by heart as morning and evening prayers. Praying them is how the three theological virtues are exercised deliberately rather than assumed.
When to Pray
Morning and evening, in moments of doubt, and whenever faith needs to be spoken aloud to become solid again.