This section and the next are headed with “The object of catechesis is expressed in profession of faith in the one God: Father, Son and Holy Spirit.” The references are to the Catechism, and there, Trinitarian formulations are in turn referenced in the patristic era formulations, as well as the New Testament. Vatican II didn’t say anything new on the Trinity, so no real surprises as to the pedigree of this material:
82. Catechesis is that particular form of the ministry of the word which matures initial conversion to make it into a living, explicit and fruitful confession of faith: “Catechesis has its origin in the confession of faith and leads to confession of faith.” (cf. 1977 Synod of Bishops, Message to the People of God, 8; Catechism 185-197)
The profession of faith inherent in Baptism (cf. Catechism 189) is eminently Trinitarian. The Church baptizes “in the name of the Father and of the Son and of the Holy Spirit” (Mt 28,19) (cf. Catechism 180-190 and 197) the triune God to whom the Christian entrusts his life. Initiatory catechesis—both before and after the reception of Baptism—prepares for this decisive undertaking. Continuing catechesis helps to mature this profession of faith, to proclaim it in the Eucharist and to renew the commitments which it entails. It is important that catechesis should unite well the confession of christological faith, “Jesus is Lord”, with the trinitarian confession, “I believe in the Father, the Son and the Holy Spirit”, in such a way that there are not two modes of expressing the Christian faith. He who is converted to Jesus Christ and recognizes him as Lord through the primary proclamation of the Gospel begins a process which, aided by catechesis, necessarily leads to explicit confession of the Trinity.
Though Christians are focused on Christ, our faith reflects the mystery of the nature of God. It’s difficult, if not impossible to perceive the Trinity. But we can be aware of the action God takes in our lives and in human history. We can distinguish the Persons.
In the confession of faith in the one God, the Christian rejects all service of any human absolute; “power, pleasure, race, ancestors, state, wealth…”, (cf. Catechism 2113) and is thus liberated from the enslavement of any idol. It is the proclamation of his will to serve God and man without any ties. In proclaiming faith in the Trinity, which is a communion of Persons, the disciple of Jesus Christ shows at once that the love of God and neighbour is the principle which informs his being and his action.
And obviously, our confession in practice is imperfect. Unfortunately individual members of the Church as well as subsets (the universal leadership, parishes, cliques, cults, etc.) do indulge these aspects of human enslavement. Fortunately, God’s grace is also at work. The believer can certainly strive to be a disciple, and to exemplify our faith in what we do and in who we are.