In The Logic of God Incarnate (Ithaca: Cornell University Press, c. 1986), Thomas Morris seeks to defend Chalcedonian Christology from charges of incoherence as well as heterodox alternatives. Whereas Morris's Our Idea of God is addressed to general readers, The Logic of God Incarnate focuses on scholarly readers, those who wrestle with the more mysterious aspects of the Christian faith.
In his Preface, after telling how his interest in the subject developed while doing graduate work at Yale, Morris says: "In the course of thinking about the Incarnation for some years now, I have come to see that a few simple metaphysical distinctions and a solid dose of logical care will suffice to explicate and defend the doctrine against all extant criticisms of a philosophical nature. That is what this book attempts to show" (p. 9).
The Incarnation, of course, makes the extraordinary claim that Jesus was in fact fully God and man. Extraordinary, however, does not mean illogical or absurd. "The Christian claim is that because of the distinctiveness of divinity and humanity, it was possible for the Second Person of the Trinity, God the Son, to take on human nature while still retaining his deity. The two particular natures involved, despite appearances to the contrary, allowed this unusual duality" (p. 40). In becoming man, the Son did not lose or even temporarily surrender His divinity--Morris respects, but does not accept, what he regards as a fatal compromise implicit in kenotic Christology. In being assumed by God, the man Jesus did not lose his humanity--though we must understand that his humanity was "fully human," realizing God's design for man, not the "merely human" being we tend to think of, taking ourselves as models. Accordingly, "The God-man is, according to orthodoxy, both fully human and fully divine, but at the same time more deeply or fundamentally divine than human. The Person bearing the two natures is an essentially divine Person" (p. 52).
Taking such a strong position concerning Christ's divinity, Morris turns to explaining how divine attributes (omnipotence; omniscience; goodness; etc.) could be present in a fully human person, Jesus Christ. He argues for what he calls a "two minds view of Christ" whereby in becoming man "God the Son did not give up anything of deity; he merely took on the nature and condition of humanity" (p. 104). The "two minds view" suggests Jesus Christ combined deity and humanity in somewhat the same way we combine our conscious and unconscious minds. Our unconsciousness always underlies our consciousness, though we generally function in accord with our consciousness. Thus Jesus generally functioned in accord with his humanity, but his deity was always more basic and formative.
Taking this position, of course, commits Morris to the somewhat unfashionable defense of the "impeccability" of Christ. If God cannot sin, God's Son, fully God, cannot sin either. This does not, of course, mean that he was not fully human, since sinning is hardly a necessary quality of humanity! "Merely human" beings may unfailingly sin, but "fully human" beings need not! Thus Jesus the God-man could not have sinned. He could, however, have felt the power of temptation in his humanity. There are, analogously, "epistemic" possibilities which we con¬sciously consider without them being in fact "real." I can know, it seems to me, what it means to be a NBA superstar like Michael Jordan, though to actually be one is impossible. (Morris sets forth a better, multi-paged illustration concerning a hypnotized patient). So, he argues, "In order that he suffer real temptation, then, it is not necessary that sinning be a broadly logical or metaphysical possibility for Jesus; it is only necessary that it be an epistemic possibility for him" (p. 148).
Morris has set forth a persuasive case. He clearly thinks before he writes, uses words carefully, and seeks to make the Christian position as logical and coherent as possible. While he nowhere suggests one can convert skeptics to Christianity simply through logic, for only the Holy Spirit seems able to accomplish that, he successfully shows how believers need not fear their faith is logically flawed and defensible only through the refuge of incomprehensible "paradoxes."