Well, we don’t really know exactly WHEN
Deum de Deo got into the Latin form of the Constantinopolitan Creed. The Creed of Nicea did seem to have the words, but
authors seem to have just ascribed it as an interpolation, made perhaps accidentally by a scribe who jumbled up the two formulas together.
What we do know is, the Constantinopolitan Creed as quoted in the Councils of Toledo, which would later be the basis of the text of the Creed in the Mozarabic Rite (
Credimus in unum Deum), already contain this ‘God of God’ clause, in the form of
Deum ex Deo. The first time it is quoted is in the Third Council of Toledo (589):
Credimus in unum deum patrem omnipotentem factorem caeli et terrae, visibilium omnium et invisibilium conditorem, et in unum dominum Iesum Christum filium dei unigenitum, ex patre natum ante omnia saecula.
Deum ex deo, lumen ex lumine, deum verum, ex deo vero. Natum non factum
homousion patri, hoc est eiusdem cum patre substantiae. Per quem omnia facta sunt, quae in caelis et quae in terris sunt. Qui propter nostram salutem descendit, et incarnatus est de spiritu sancto et Maria virgine. Homo factus, passus est sup Pontio Pilato, sepultus, tertia die resurrexit. Ascendit in caelos, sedet ad dexteram patris. Iterum venturus in gloria iudicare vivos et mortuos. Cuius regni, non erit finis, et spiritum sanctum dominum et vivificantem. Ex patre procedentem, cum patre et filio adorandum et glorificandum. Qui locutus est per prophetas. Unam catholicam atque apostolicam ecclesiam. Confitemur unum baptisma in remissionem peccatorum. Expectamus resurrectionem mortuorum, vitam futuri saeculi. Amen.
It is again quoted in the
Eighth,
Twelfth, and
Thirteenth councils (each with some variances in wording), albeit, they all now have in the part concerning the Holy Spirit:
ex Patre et Filio procedentem.
We must need to mention that the Church of Rome was one of the latest to introduce the custom of reciting the Creed at Mass. The Spanish were the first in the West to introduce it (in the East the custom already existed), and from Spain the usage spread into Gaul. In Rome, the Creed was given a place at the third scrutiny before solemn baptism (during Lent), when it was taught to catechumens in both Greek and Latin. The text of the Creed as found in the
Gelasian Sacramentary is notable in that it differs from the text we are all familiar with, being on the face of it a more literal translation of the Greek text - it doesn’t have the Latin-specific
Deum de Deo or the
Filioque (albeit some versions apparently alter the text to conform to the later form; cf.
pp. 55-57)!
Credo in unum Deum, Patrem omnipotentem, factorem caeli et terrae, visibilium omnium et invisibilium.
Et in unum Dominum Iesum Christum, Filium Dei unigenitum; de Patre natum ante omnia saecula; lumen de lumine, Deum verum de Deo vero; natum, non factum; consubstantialem Patris; per quem omnia facta sunt; qui propter nos homines, et propter nostram salutem descendentem de caelis; et incarnatum de Spiritu sancto et Maria virgine, et humanatum; crucifixum etiam pro nobis sub Pontio Pilato, et passum et sepultum; et resurgentem tertia die secundum Scripturas; et ascendentem in caelos, et sedentem ad dexteram Patris; et iterum venturum cum gloria iudicare vivos et mortuos, cuius regni non erit finis.
Et in Spiritum sanctum Dominum et vivificatorem; ex Patre procedentem; qui cum Patre et Filio simul adoratum et conglorificatum: qui locutus est per prophetas.
In unam, sanctam, catholicam, et apostolicam ecclesiam. Confiteor unum baptisma in remissionem peccatorum. Spero resurrectionem mortuorum, et vitam futuri saeculi. Amen.