The mystery of the one God revealed in history as Father, Son, and Spirit was from the very beginnings of Christianity never a mere mathematical or logical puzzle. Rather Christians experience this divine one-in-three or triune reality as a saving and gracious mystery, sharing its life with humans through creation, redemption, and sanctification. God is understood as a mystery of communion—communion among Father, Son, and Spirit, and communion between these three divine "persons" and each human person. Furthermore, this double communion is also experienced as the basis of and condition of possibility for the communion among humans themselves, in the Church and in the world at large. These three intrinsically interrelated communions—communion among the three divine persons, communion between the divine persons and each human person, and communion among all humans with and in the cosmos—constitute for Christians the goal and meaning of human history and the universe.
New Testament Roots. This faith in the one God as Father who communicates Himself to humans in His Son and by the power of His Spirit is already expressed in the New Testament, especially by means of triadic formulas that entail both distinction and equality among the three divine persons (e.g., Mt 28:19; 2 Cor 13:13; Eph 2:18; 3:14–17; 4:4–6; 5:18–20; Rom 8:14–17, etc.). Beside the Father, both Christ and the Spirit are referred to as "Lord" and divine attributes are predicated of Jesus and, to a lesser extent, of the Spirit. In His preexistence (Jn 1:1–18: Heb 1:1–3), conception (Mt 1:23; Lk 1: 32), baptism (Mk :11), transfiguration (Mk 9: 2–13), and Resurrection (Rom 1:4) Jesus is confessed to be the beloved Son of God in power. Similarly, though less explicitly, the Holy Spirit is depicted not only as a divine power but also as a divine "person" speaking though the mouths of the apostles (Acts 8:20), sending the disciples out on mission (Acts 13:4), leading the Church (Acts 20:28), and dwelling in Christians to give them life and to bear witness to their being a son or daughter of God (Rom 8:14–16; Gal 4:6). For this reason "God," "Lord," and "Spirit" can be used in parallelism to one another (1 Cor 12: 4–6; 2 Cor 3:17).
For the first Christians who were Jews, this faith in the triune God was bound to be baffling in light of their unqualified monotheism. As a result, there is already in the New Testament an attempt to justify this Trinitarian faith by clarifying the relationships among the Father, Son, and Spirit, even though there is no elaboration of a Trinitarian theology as such in the New Testament. Most prominent is the Fourth Gospel's teaching on the two "sendings" or "processions," namely that of the Son from the Father (Jn 3:17, 34; 6:38; 20:21) and that of the Spirit from the Father and/through the Son (Jn 14:16–17, 26; 15:26). Of course, the focus in these Johannine texts is on the sendings and processions of the Son and the Spirit in the history of salvation (the oikonomia ), on what is termed the "economic Trinity," and not on their eternal origination in the Godhead (the theologia ), within what will be termed the "immanent Trinity." In later theologies of the Trinity, however, these texts will be invoked to explain the eternal relationships among the Father, Son, and Spirit within the Godhead itself, in other words, the divine "processions."
Underlying Theological Issues. The Christian understanding of God can be summarized in two statements. First, in continuity with the faith of Israel, it is affirmed that there is only one God, and God is Yahweh, the Father. In light of later Latin theology, it is important to note that in the New Testament and in the pre-Nicene theology, "the one God" refers to the Father and not to the divine nature or substance that the three divine persons possess in common. Second, this one God the Father is confessed to have manifested himself in the End Time, that is, in the life-death-resurrection of Jesus and in the outpouring of the Spirit, as the Father of Jesus who is therefore the Son and as the Sender of the Spirit who therefore proceeds from Him. Hence, Jesus the Son and the Holy Spirit are divine and not created. The one God is therefore somehow a Triad. The theological challenge is how to maintain these two apparently contradictory statements together, in such a way that the one God does not become a monad, and a divine triad does not jeopardize the monotheistic faith, and to come up with a plausible explanation of how unity and trinity in God are not mutually contradictory.
Historically, three positions regarding the Triune God have been condemned as heretical. First, subordinationism, which holds that the Logos/Son and the Spirit are not divine but created. Arius, who taught that the Logos is not eternal but only a preeminent creature, was condemned by the Council of Nicaea (325), and the "pneumatochoi" or Macedonians, who held that the Spirit is a creature, were rejected by the Council of Constantinople (381). Second, modalism, which denies that Father, Son, and Spirit are distinct realities, and comes in two forms. Some, like Noetus, Praxeas, and Sabellius thought that "Father," "Son," and "Spirit," are mere names for the various roles of the one Godhead in the economy ("Modalist Monarchians"), while others thought that Christ was a mere man indwelt or inspired in a special way by divine power ("Adoptionist" or "Dynamic Monarchians"). Third, Economic Trinitarianism, whose classic defender is Tertullian and which holds that God in His eternal being is a strict Monad, but becomes a Triad in His decision to create, when God's immanent Word (the Logos endiathetos ) was uttered forth in creation and Incarnation (the Logos prophorikos ) and when, in a similar fashion, God's inner Spirit was breathed forth into the world.
The first attempt at reconciling God's unity and trinity by way of processions was made by the Cappadocian Fathers who drew a distinction between that which is generic or common (to koinon ) shared equally by all members of a class and that which is particular or individual (to idion ) possessed by a particular member and no other. That which is common and answers the question of "what" is called nature (ousia ), whereas that which is particular and answers the question of "who" is person (hypostasis ). Hence, ousia + idioma = hypostasis. Applying this distinction to God, the Cappadocians argue that what is common in God is the divine nature (ousia ) and that this divine nature is particularized by the characteristics that constitute their persons (hypostasis ). These characteristics (idiomata ), which differentiate one divine person from another, are brought about by the ways in which the Son and the Spirit originate or proceed from the Father: The Father is unoriginated (agennesia ), the Son is generated (gennesia ), and the Spirit proceeds (ekporeusis or ekpempsis ).
The Legacy of Augustine, Thomas Aquinas, and Scholastic Theology. The first comprehensive attempt at explaining the compossibility between unity and trinity in God was made by augustine in his De Trinitate. Augustine chooses as the starting point of his Trinitarian theology the unity of the one divine substance or nature, which unfolds subsequently as it were into three persons, Father, Son, and Spirit. The bishop of Hippo effectively abandons the earlier tradition that the one God is first and foremost the Father, and that the unity and unicity of God resides in the Father. This is a momentous methodological change, with far-reaching implications for the way in which the relationships between each divine person and humans are understood. In fact, for Augustine, and through him, thomas aquinas and scholastic theology, since there is only one substance and since substance is the basis of action, all the divine attributes as well as the operations of God in the history of salvation (the opera divina ad extra ) are to be predicated of God absolutely and not relatively of particular persons. Consequently, it is only by way of appropriation that these actions are attributed to a particular divine person on the basis of some affinity between these actions and the distinctive characteristics (proprium ) of that person. An unintended but disastrous result of this approach is a separation between the Immanent Trinity (which is truly a Triad) and the Economic Trinity (which is not Trinitarian but fundamentally unitarian, namely, the divine substance).
Augustine devotes the second half of his De Trinitate to exploring the analogies of the Trinity in humans, since humans are created in the image and likeness of God. He first considers the triad involved in the phenomenon of human love—the Lover, the Loved, and the Love—but abandons it because it does not appear to him to adequately reflect the divine Triad's equality. He then investigates the rational processes of the human mind and finds them more satisfactory: the mens or memoria, the intellectus, and the voluntas. By mens or memoria Augustine means the person's self-consciousness. This self-consciousness is actualized in the act of knowing and the act of willing. There is then a three-in-one triad in human cognition: the mind, its knowledge of self, and its love of self. The mind, the originating source of the whole cognitive process, is analogized to the Father; the production of knowledge by the mind resulting in the knowledge of itself, i.e., the "conception" of the idea, is analogized to the generation of the Son/Word/Image by the Father; and the termination of the rational process in love is analogized to the procession of the Spirit from the Father and the Son, who, according to Augustine is the mutual love between the Father and the Son. These reflections serve as the foundation of the later theology of divine processions as elaborated by Thomas Aquinas and popularized by scholastic theology.
By "procession" is meant the origination or coming forth of one being from another. Derived from biblical texts such as Jn 15:26 ("the Spirit of truth, who proceeds [ekporeuetai ] from the Father"), the term is used in theology to explain how the Son and the Spirit originate from the Father eternally in the Godhead. Thomas Aquinas's interpretation (Summa Theologiae I, q. 27) later popularized by scholastic theology, remains the best known. Thomas begins by positing a real distinction between the principle or source from which something proceeds, and the term or that which proceeds from the principle or source. Furthermore, he notes that there are two kinds of procession: the transient (ad extra ), in which the term comes to exist outside the principle, e.g., the chair exists outside the carpenter, and the immanent (ad intra ), in which the term remains within the principle, e.g., the idea or concept remains within the mind that conceives it.
The two eternal processions in the Godhead belong to the second kind. They are not produced in time by God the Father by way of efficient causality like creatures. Rather they are eternal "events" within the Godhead itself by which the Godhead is a triad, all three members of which are truly and equally divine. Taking a clue from Augustine, Thomas analogizes these two divine processions to the two activities of the human spirit, namely, knowing and loving. The first procession, that of the Son/Word, is termed by the Bible as "generation." In generation, there are three things: the vital act whereby something is given birth by another living thing, the specific resemblance between the generator and the generated, and the identity of nature between the two. These three things are found, analogously, in the generation of an idea by the mind, and the generation of God the Son from God the Father. The Father contemplates Himself eternally and generates in the divine mind a perfect idea or word or image of Himself, just as when a person conceives in the mind an idea that is identical in nature with the mind. Hence the Son can be said to be the Word, Wisdom, the Image of God.
Beside the procession of the Son by generation the Bible also speaks of the procession of the Spirit from the Father. This procession may be analogized to another act of the human spirit, namely, willing or loving. In the cognitional process of the human spirit, what is known is also often loved. The act of knowing is different from that of love, which proceeds from the will, and not the intellect. Analogously, God the Father loves the Son and vice versa, through the divine will. This mutual love between the Father and the Son is the Spirit. Whereas there is a specific term in the Bible to refer to the act whereby the Son proceeds from the Father, namely, generation, there is none to describe the procession of the Spirit. This procession ought not to be called "generation" but "spiration" or breathing-forth, an act of communication through love. Hence, the names of the Spirit are Gift and Love, and not Son.
In the Bible the Spirit is said not only to proceed from the Father (Jn 15:26) but also to have been sent by the Father and the Son (Jn 14:26; 15:26). In light of this, Latin theology (e.g., Augustine, Anselm of Canterbury, and Thomas) holds that the Spirit proceeds from the Father and the Son but as from one principle, even though the Creed of the Council of Constantinople professes only that the Spirit "proceeds from the Father." This socalled double procession of the Spirit constitutes a longstanding difference between the Latin and Orthodox Churches, a difference exacerbated by ecclesiastical and political rivalries.
Contemporary Theology. Despite the enormous authority of Augustine and Thomas Aquinas behind this "psychological theory" of the Trinity, many contemporary theologians have found it ultimately unsatisfactory. Though it clarifies in some way how faith in the one and trine God is not self-contradictory, the speculation on the divine processions by way of intellect and will is arid and unbiblical. As a result, some theologians have dropped it altogether and even suggest that no discourse on the Immanent Trinity is possible or useful. Others argue that the language of origination or procession implies hierarchy and subordination and negates the equality among the three divine persons.
The most serious critique, however, comes from Karl rahner and his many followers. For them, the psychological theory of the divine processions implicitly separates the divine nature from the divine persons, even though it explicitly affirms that the divine persons are identical with the divine nature. Because it is assumed that the starting point for the theology of the Trinity is the divine substance, and not the Father, God is said to act in the history of salvation through the divine substance, so that all the divine actions ad extra are to be attributed to the common substance and not to each of the divine persons. This is the teaching of the Fourth Lateran Council (1215), the Council of Florence (1442), and later scholastic theology: opera divina ad extra communia sunt tribus personis tamquam uno principio (divine actions outside of the Trinity are common to all three persons as one principle). It is only by way of appropriation that God's actions in history can be attributed to a particular divine person. As a consequence, there is a loss of the Economic Trinity in theology, and Christians, despite their professed faith in the Trinitarian God, are in fact "monotheists" or unitarians.
To retrieve the Economic Trinity Rahner affirms the principle that "the 'economic' Trinity is the 'immanent' Trinity and the 'immanent' Trinity is the 'economic' Trinity." What Rahner intends with this formula is to assert that God acts in history not through the divine nature but through each divine person, each in a distinctive way, so that humans are related to each divine person relatively and distinctively, and not to the divine substance absolutely. In the concrete, "God" does not refer to the divine substance but to the Unoriginated and Originating Father who acts in history in two really distinctive (therefore not modalist) and ordered (therefore mutually conditioned) ways, in the Incarnation of the Logos under the aspects of origin, history, invitation, and knowledge, and in the grace of the Spirit under the aspects of future, transcendence, acceptance, and love. Consequently, the ways in which we experience God in history (the Economic Trinity) do tell us really and truly, though never exhaustively, about the ways in which the Father, the Son, and the Spirit are related to each other eternally (the Immanent Trinity). God's communication to us is indeed self -communication. This self-communication is therefore to be understood not by way of efficient causality by which God creates something distinct from Himself but by way of formal or more precisely quasi-formal causality by which the three divine persons indwell in humans, each in its distinctive way.
Consequently, speaking about the two temporal ways of God's self-communication by means of narrative and/or metaphysical language is already speaking about the two eternal "processions" from the Father. Trinitarian theology is not something one does after one has dealt with the "one God" (divine substance, its existence and its attributes). Rather it is the systematic and critical reflection on the two ways in which God the Father has acted in history by way of self-communication and on what these two ways reveal about who God is, that is, one and trine, or on how the Son and the Spirit "proceed" from the Father.
See also : trinity, holy, articles on.
Bibliography: k. rahner, The Trinity, tr. j. donceel (New York 1974). t. marsh, The Triune God: A Biblical, Historical, and Theological Study (Mystic, Conn. 1994). g. o'collins, The Tripersonal God: Understanding and Interpreting the Trinity (New York 1999). c. lacugna, God for Us: The Trinity & Christian Life (San Francisco 1991). e. johnson, She Who Is (New York 1993). d. coffey, Deus Trinitas: The Doctrine of the Triune God (New York 2000). p. c. phan, "God in the World: A Trinitarian Triptych," in New Catholic Encyclopedia, Jubilee Volume: The Wojtyła Years, ed. b. l. marthaler (Washington, D.C. 2001) 33–42.
[p. c. phan]