4. Catholic belief in the Most Holy Trinity, and especially in the Holy Spirit. Once the mystery of the divine and eternal person of Christ the Son of God is abandoned, the truth respecting the Most Holy Trinity is also undermined, and with it the truth regarding the Holy Spirit who proceeds eternally from the Father and the Son, or from the Father through the Son (10). Therefore, in view of recent errors, some points concerning belief in the Most Holy Trinity, and especially in the Holy Spirit, are to be recalled to mind.
The Second Epistle to the Corinthians concludes with this admirable expression: “The grace of our Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all” (11). The commission to baptize, recorded in St. Matthew’s Gospel, names the Father, and the Son, and the Holy Spirit as the three pertaining to the mystery of God and it is in their name that the converts must be reborn (12). Lastly, in St. John’s Gospel, Jesus speaks of the coming of the Holy Spirit: “When the Paraclete comes whom I will send you from the Father, the Spirit of truth who proceeds from the Father, he will give testimony of me” (13).
On the basis of the indications of divine Revelation, the Magisterium of the Church, to which alone is entrusted “the office of authentic interpretation of the word of God, written or handed down” (14), acclaims in the Creed of Constantinople “the Holy Spirit, Lord and giver of life… who together with the Father and the Son is adored and glorified” (15). In like manner the Fourth Lateran Council taught that it is to be believed and professed “that there is but one only true God… Father and Son and Holy Spirit: three persons indeed, but one essence…: the Father proceeding from none, the Son from the Father alone and the Holy Spirit equally from both, without beginning, always, and without end” (16).