In John 16: 12-15, Christ talks to his disciples of the work of the Spirit. This reading, brief as it is, is a clear portrayal of the Divine economy of each of the persons of the Holy Trinity. The word "Trinity," does not appear in Sacred Scripture. It is a word that Holy Mother Church, in her divinely endowed wisdom, attributes to God in describing His Triune nature.
“I have much more to tell you, but you cannot bear it now. But when he comes, the Spirit of truth, he will guide you to all truth. He will not speak on his own, but he will speak what he hears, and will declare to you the things that are coming. He will glorify me, because he will take from what is mine and declare it to you. Everything that the Father has is mine; for this reason I told you that he will take from what is mine and declare it to you."
(John 16: 12-15 NAB)
Jesus tells the Disciples here that the Holy Spirit's work is to bring about a clarity in revelation, bringing to completion Christ's teaching ministry. It is this very power of the Holy Spirit that is at work in Magisterial teachings, rendering them infallible for the sake of the souls of the baptized. This is what justification by a living faith means, that enables us to "have peace with God through our Lord Jesus Christ" (Romans 5:1). This same Spirit grants the authority of God to His Children. The baptized, in adhering to the Spirit within Christ and His Church share in the divine life and authority of God in revealing His truth to the world, living it out in life and Liturgy.
Thus, the Holy Spirit continues of the Messianic ministry of Christ. This Holy Spirit, the Ruach HaKodesh for the Jewish Christians, is the Spirit of all Truth. As such, in pronouncing the words above. Christ effectively authenticates for the future, all aspects of the faith as handed down by the Magisterium, including the infallibility of Sacred Scripture, Sacred Tradition, and Sacred Liturgy. It is only within this rich reality that we come to realize how, "the love of God has been poured out into our hearts through the holy Spirit that has been given to us" (Romans 8:5)
At its core, what needs to be remembered here is that Christianity is far more than a Religion of the Book, it is a Religion of a Person. This is the very heart of Christianity. Revelation begins with the Person of the Father, comes in its fullness comes to us in the Person of Christ, and is brought to a fuller understanding through the Person of the Spirit. Christ is, in His own words, "“[begotten of the LORD], the beginning of his works, the forerunner of his deeds of long ago" (Proverbs 8:22).
Divine Revelation is not merely about fact, it is a living person in the Triune God who invites us to share in His own divine life. This is why the Psalmist sings with utmost Joy, "What is man that you are mindful of him, and a son of man that you care for him? Yet you have made him little less than a god, crowned him with glory and honor" (Psalm 8:5-6) These truths are revealed to us, as Aquinas says, principally for the salvation of our souls, that we may come to share eternally in the divine life of the Holy Trinity in Heaven. The only way to this eternal beatitude, therefore, is to proclaim the Lordship of the Trinity over our entire life.
Glory to the Father, the Son, and the Holy Spirit; to God who is, who was, and who is to come, for ages unending, Amen.