The unity of God as understood by four twentieth century trinitarian theologians: Karl Rahner, Millard Erickson, John Zizioulas, and Wolfhart Pannenberg

This dissertation seeks to discern how the triune God is one. It critically examines the understandings of trinitarian unity proposed by Karl Rahner, Millard Erickson, John Zizioulas, and Wolfhart Pannenberg in historical, logical, theological, and Christological terms. Chapter 1 suggests that historically the unity of God was understood to lie in both the derivation of the Son and Spirit from the Father and the common divine substance, and that a proper doctrine of trinitarian unity must correspond to the biblical statements regarding a sole creator, must deal coherently with the attributes of God, and must accommodate a Chalcedonian Christology.; Chapter 2 critiques the position of Karl Rahner. Rahner presents a relative trinitarianism revised to incorporate his theology of symbol. Rahner's position is shown to overemphasize the priority of the Father, and to face difficulties because of its insistence that God is only one person, or center of consciousness, and that the Father reveals himself through the Son and Spirit.; Chapter 3 critiques the position of Millard Erickson. Erickson presents a social trinitarianism, emphasizing the complete equality and personality of the persons as Leonard Hodgson did. His position is shown inadequate to explain God's unity, aseity, and status as a single creator.; Chapter 4 critiques the position of John Zizioulas. Zizioulas draws from the Cappadocians to develop a personal ontology in which the Father generates the Son and Spirit and thereby the triune communion, which is the Father's essence. Zizioulas's position is shown to distort the Cappadocian position, to face logical difficulties, and to drift towards tritheism.; Chapter 5 critiques the position of Wolfhart Pannenberg Pannenberg bases his understanding of God's unity on the divine essence, which he believes to be rule, love, and spirit. His position is shown to be hampered by obscurity, an inconsistent methodology, irreconcilable definitions of God's essence, and an unacceptable Christology.; Chapter 6 offers suggestions for the construction of an evangelical doctrine of trinitarian unity. It exhorts theologians to be clear, retain the concepts of essence and the divine monarchy, and respect tradition. It concludes with a sketch of a position which follows these exhortations.