1 By believing In One God we cut off all misbelief in many gods, using this as a shield against Greeks; and every opposing power of heretics; and by adding, In One God the Father, we contend against those of the circumcision, who deny the Only-begotten Son of God. For, as was said yesterday, even before explaining the truths concerning our Lord Jesus Christ, we made it manifest at once, by saying “The Father,” that He is the Father of a Son: that as we understand that God is, so we may understand that He has a Son. But to those titles we add that He is also “Almighty;” and this we affirm because of Greeks and Jews together, and all heretics.
Source: Catechetical Lectures (New Advent)