Act of Faith
Actus Fidei
The three Acts were written so that a Christian could put the theological virtues into words, and catechisms have taught them since the 18th century; the Baltimore Catechism made this wording familiar in English. This one states the Trinity, the Incarnation and the Judgment, then gives the reason for believing: God has revealed it and cannot lie. Many prayer books place all three at the start of morning prayers.
Traditional, catechism tradition; Baltimore Catechism
O my God, I firmly believe
that you are one God in three divine Persons,
Father, Son, and Holy Spirit.
I believe that your 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 you have revealed them,
who can neither deceive nor be deceived.
Amen.