The Christian God

The central thesis is that the distinctively Christian doctrines of the Trinity and the Incarnation are logically coherent and can be articulated within the framework of analytic philosophy. Swinburne argues that the Christian God is one substance in three divine persons, and that the second person became human while remaining divine . The book is the fourth volume in a tetralogy that began with The Coherence of Theism (1977), continued with The Existence of God (1979) and Faith and Reason (1981), and includes Revelation (1992). It presupposes the philosophical framework developed in those earlier volumes, particularly the account of God as a temporal, omnipotent, omniscient spirit, and applies it to the specific doctrines of Christian faith.

Swinburne defends the coherence of the Trinity by distinguishing between substance and person. He argues that the divine substance is one, but that it exists in three distinct persons who share that substance. This is not a contradiction because 'substance' and 'person' are different categories: the Father, Son, and Spirit are three persons, but they are one God because they share the same divine substance . Swinburne's account is a form of social trinitarianism, though he prefers to speak of the three persons as distinct centers of consciousness and will who are united by their shared divine nature. The key move is to show that the doctrine does not entail that there are three Gods, because the persons do not have separate substances.

Swinburne argues that the Incarnation is coherent because it is possible for a divine person to acquire a human nature without ceasing to be divine. The second person of the Trinity, the Son, took on a human body and a human soul, so that he became fully human while remaining fully divine . This is not a contradiction because divinity and humanity are not incompatible properties: a person can have both a divine nature and a human nature, as long as the natures are properly understood. Swinburne's account is broadly in line with the Chalcedonian definition, which affirms that Christ is one person in two natures. The book's contribution is to show that this definition can be stated in the terms of contemporary analytic philosophy without incoherence.

The Christian God is the fourth and final volume of Swinburne's tetralogy on philosophical theology. The first volume, The Coherence of Theism (1977), establishes that theism is logically coherent; the second, The Existence of God (1979), argues that the evidence makes theism more probable than not; the third, Faith and Reason (1981), addresses the rationality of religious belief; and the fourth, Revelation (1992), examines how a divine revelation could be identified . The Christian God presupposes the results of these earlier volumes and applies them to the specific doctrines of Christianity. It is the most explicitly theological of the four, and it is best read after the others, though it can be read independently by readers familiar with Swinburne's framework.

The book was well received by analytic theologians but criticized by those who found Swinburne's approach too rationalistic. Some critics argued that his account of the Trinity is not sufficiently orthodox, because it treats the three persons as distinct centers of consciousness in a way that risks tritheism. Others argued that his account of the Incarnation is too abstract, and that it does not do justice to the biblical and creedal affirmations about Christ. Still others argued that Swinburne's philosophical framework is too narrowly analytic to capture the richness of Christian doctrine. Swinburne responded to these criticisms in subsequent work, but the book remains a standard reference point for analytic discussions of the Trinity and Incarnation.

The most common misunderstanding is that Swinburne is defending a form of tritheism—the belief in three Gods. He is not. His account insists that there is one divine substance, and that the three persons are one God because they share that substance . A related misunderstanding is that Swinburne is reducing the Trinity to a logical formula that loses its devotional and liturgical significance. He is not: he is arguing that the doctrine is coherent, not that coherence is all that matters. The book is a work of philosophical theology, not a devotional manual, and its aim is to show that the central doctrines of Christianity can be stated without contradiction. Readers who expect a spiritual meditation will be disappointed; readers who want a rigorous defence of orthodoxy will find one.