109 The whole Church is called to evangelization and to the witness of a life of faith, by the fact that she has been made a sharer in the munus propheticum of the Lord Jesus through the gift of his Spirit. Thanks to the permanent presence of the Spirit of truth in the Church (cf. Jn 14:16-17), "the universal body of the faithful who have received the anointing of the holy one (cf. 1 Jn 2:20, 27) cannot be mistaken in belief. It displays this particular quality through a supernatural sense of the faith in the whole people when, 'from the Bishops to the last of the lay faithful ', it expresses the consensus of all in matters of faith and morals". In order to carry out her prophetic mission, the Church must constantly reawaken or "rekindle" her own life of faith (cf. 2 Tim 1:6), particularly through an ever deeper reflection, under the guidance of the Holy Spirit, upon the content of faith itself. The "vocation" of the theologian in the Church is specifically at the service of this "believing effort to understand the faith". As the Instruction Donum Veritatis teaches: "Among the vocations awakened by the Spirit in the Church is that of the theologian. His role is to pursue in a particular way an ever deeper understanding of the word of God found in the inspired Scriptures and handed on by the living Tradition of the Church. He does this in communion with the Magisterium, which has been charged with the responsibility of preserving the deposit of faith. By its nature, faith appeals to reason because it reveals to man the truth of his destiny and the way to attain it. Revealed truth, to be sure, surpasses our telling. All our concepts fall short of its ultimately unfathomable grandeur (cf. Eph 3:19). Nonetheless, revealed truth beckons reason — God's gift fashioned for the assimilation of truth — to enter into its light and thereby come to understand in a certain measure what it has believed. Theological science responds to the invitation of truth as it seeks to understand the faith. It thereby aids the People of God in fulfilling the Apostle's command (cf. 1 Pet 3:15) to give an accounting for their hope to those who ask it". It is fundamental for defining the very identity of theology, and consequently for theology to carry out its proper mission, to recognize its profound and vital connection with the Church, her mystery, her life and her mission: "Theology is an ecclesial science because it grows in the Church and works on the Church... It is a service to the Church and therefore ought to feel itself actively involved in the mission of the Church, particularly in its prophetic mission". By its very nature and procedures, authentic theology can flourish and develop only through a committed and responsible participation in and "belonging" to the Church as a "community of faith". In turn, the fruits of theological research and deeper insight become a source of enrichment for the Church and her life of faith.
Source: Veritatis Splendor (Vatican.va)