They may conjure up images of medieval witch trials and whatnot, but heresies are really nothing to get into a fuzz about. Well, the specific heresies may be, but the fact that the Church calls certain beliefs and opinion heretical should not. A heresy is nothing more complicated than a teaching that undermines the faith in a grave enough manner that supporting, promoting or following it has a serious penalty as a consequence. And that because such a heresy endangers the souls of the faithful.
One such heresy that I came across today* has several names, but most people who know it, will know it as modalism or Sabellianism. A short definition would be that modalism holds that the Father, Son and Holy Spirit are merely three ways, or modes, in which God has revealed Himself to people.
Why is this a heresy? Why can’t the Father, Son and Holy Spirit not be three forms in which God interacts with us? Well, for starters, it would make His own existence, as we have come to know it, a fake. Countless times do we read in the Gospels how Jesus prays to His Father. If both were just roles played by the one God, why would He do that? In the Prologue of the Gospel of John we read that the Word was God and was with God. The Word of God is Jesus, the Son, but why, if the Son and the Father are the same, would John tell us that the one was with the other? In Genesis, we read about the spirit of God hovering over the deep. Not God, but His Spirit. Why would God play a role before an empty deep?
There is one God in three Persons. These three Persons are not the same. They are separate and unique, but they are all equally God. This is a mystery of our faith, which means that it is something that goes beyond our understanding. It is good that some things are beyond our ken, because God is not limited to the understanding of his creatures. If He were, He would be limited. A two-dimensional creature has no way of understanding three or even four dimensions. We have no way of understanding or even imagining the five, six or more dimension that scientists say exist. And we have no way of grasping the Trinity, but that has no bearing on its reality.
Is the Trinity unlikely? Perhaps. But it is what God has taught us, through Jesus’ prayers, and through the work of the Holy Spirit.
In articles 253 to 255, the Catechism of the Catholic Church delves into the Trinity. It has this to say [emphasis mine, notes removed for ease of reading]:
253 The Trinity is One. We do not confess three Gods, but one God in three persons, the “consubstantial Trinity”. The divine persons do not share the one divinity among themselves but each of them is God whole and entire: “The Father is that which the Son is, the Son that which the Father is, the Father and the Son that which the Holy Spirit is, i.e. by nature one God.” In the words of the Fourth Lateran Council (1215), “Each of the persons is that supreme reality, viz., the divine substance, essence or nature.”
254 The divine persons are really distinct from one another. “God is one but not solitary.” “Father”, “Son”, “Holy Spirit” are not simply names designating modalities of the divine being, for they are really distinct from one another: “He is not the Father who is the Son, nor is the Son he who is the Father, nor is the Holy Spirit he who is the Father or the Son.” They are distinct from one another in their relations of origin: “It is the Father who generates, the Son who is begotten, and the Holy Spirit who proceeds.” The divine Unity is Triune.
255 The divine persons are relative to one another. Because it does not divide the divine unity, the real distinction of the persons from one another resides solely in the relationships which relate them to one another: “In the relational names of the persons the Father is related to the Son, the Son to the Father, and the Holy Spirit to both. While they are called three persons in view of their relations, we believe in one nature or substance.” Indeed “everything (in them) is one where there is no opposition of relationship.” “Because of that unity the Father is wholly in the Son and wholly in the Holy Spirit; the Son is wholly in the Father and wholly in the Holy Spirit; the Holy Spirit is wholly in the Father and wholly in the Son.”
But who’s to say that what the Church teaches through the Catechism is right? That belief, that trust in the dogmatic teachings of the Church flows directly from th words of Jesus and the belief in the Holy Spirit who guides us. If we express faith in His words to St. Peter, “I will give you the keys of the kingdom of Heaven: whatever you bind on earth will be bound in heaven; whatever you loose on earth will be loosed in heaven” (Matthew 16:19), and in the Holy Spirit of Pentecost, we must als have faith in the Church that Christ established upon Peter, and the faith that she safeguards and communicates.
God is Triune: one Being in three Persons. This we know through Scripture, the Word of God, and the teachings of the Church of Christ. To say otherwise is a denial of God as He is. God does not pretend. He is who He says He is. He is the Father, the Son and the Holy Spirit, who are all true Persons, not phantasms or roles He plays before us. Because He takes us seriously, He reveals Himself to us as He is.
*The source linked to above is a Dutch text, a reflection given by lay Dominican Leo de Jong on Trinity Sunday, at the nominally Catholic church ‘Het Steiger’ in Rotterdam. In this reflection, Mr. de Jong denounces our understanding of the Trinity as three separate divine Persons as nonsense. Instead, he says, these persons are three forms in which Gods allows Himself to be known. This misleading teaching, presented as profound knowledge, is in reality a centuries-old heresy.
For a further Biblical explanation of the Trinity, go here.
Art credit:  Pope St. Clement Adoring the Trinity, by Giovanni Battista Tiepolo, 1737-1738.