Actus Fidei
The Act of Faith
An act of divine faith, believing all that God has revealed, on the authority of God who can neither deceive nor be deceived.
Domine Deus, firma fide credo et confiteor
omnia et singula quae sancta Ecclesia Catholica proponit,
quia tu, Deus, ea omnia revelasti,
qui es aeterna veritas et sapientia,
quae nec fallere nec falli potest.
In hac fide vivere et mori statuo.
Amen.
O Lord God, with firm faith I believe and confess
each and all the things which the holy Catholic Church proposes,
because Thou, O God, hast revealed them all,
Thou who art eternal truth and wisdom,
which can neither deceive nor be deceived.
In this faith I resolve to live and to die.
Amen.
Translation source: fisheaters.com/prayers.html
About this prayer
Faith, hope, and charity are the three theological virtues, infused into the soul at Baptism, by which the Christian is ordered directly to God. The Church bids the faithful to make acts of these virtues often, so that what is given as a seed in Baptism may grow and bear fruit. By the Act of Faith the soul assents to all that God has revealed, not because it comprehends the mysteries by reason, but because God, who is eternal Truth and Wisdom, can neither deceive nor be deceived.
This received Latin form professes belief in each and all the things which the holy Catholic Church proposes, for the Church is the divinely appointed guardian and teacher of revealed truth. The act is fittingly made upon waking, before the reception of the Sacraments, and in any time of doubt or temptation against the Faith. The Church has long enriched the devout making of the three theological acts with her indulgences.