I worked this out in conjunction with my duties as preceptor (assistant instructor, discussion leader) for one of the introductory theology courses here at PTS. It summarizes the argument and high-points of the various chapters of Nyssen's Great Catechism so that one can more easily grasp the whole. Any beginning theology students who come across this synopsis are encouraged to treat it as a reading guide to help them better grasp what Nyssen is up to, but they should under no circumstances employ it as a substitute for actually reading Nyssen's text. - WTM
Chapters 1 & 2: An unfolding of God’s trinitarian existence through analogy to human existence.
Chapter 3: Summary of the preceding, Christianity a mean between Hellenist polytheism and Jewish monotheism.
Chapter 4: All this grounded in Scripture, aimed at convincing a Jewish interlocutor.
Incarnation and Redemption:
Chapter 5: Setting up human participation in God / goodness, and free will is a necessary piece. Evil comes from free will. Vice is the absence of virtue.
Chapter 6: Explaining how evil / vice could arise. Humans are a mixture of intelligible and sensible elements, and are changeable. Envy is the root of vice.
Chapter 7: More of the same. There is no evil other than wickedness, and wickedness is the deprivation of good. Evil does not exist in itself but is located in the human will.
Chapter 8: Evil in the will is predicated upon an erroneous judgment about the good. Salvation conceived as our re-creation. Soul and body are joined in evil and in re-creation. Virtue heals the soul in this life, and if it is not healed now it will be hereafter. God foresaw our sin and devised a plan to fix it. Creatures are subject to change, and evil when that change is divorced from their created goodness. Revelation shows that only God is capable of saving us after our fall.
Chapter 9: Nyssen anticipates the criticism that the incarnation is degrading to God, and argues that the morally beautiful belongs to God’s being. The implication is that the incarnation is morally beautiful.
Chapter 10: Nyssen argues that there is no reason to think that divinity is circumscribed by humanity in the incarnation.
Chapter 11: There is an analogy between how the soul and body relate in human beings and how the divinity and humanity relate in Christ. Both are ineffable.
Chapter 12: Christ’s activities correspond with the divine, and this is evidence of the incarnation.
Chapter 13: Birth and death are usually considered un-divine because both involve weakness: the weakness of birth as resulting from sensual pleasure, and the weakness of death as physical decay. Neither of these things took place with reference to Christ, so no weakness in Christ’s birth and death.
Chapter 14: A pivotal question: Why did God become incarnate?
Chapter 15: We would not know God if he had not become incarnate and secured salvation’s benefits for us. Only vice opposes virtue, not materiality as such, so the incarnation does not involve God in vice and does not contradict divine goodness.
Chapter 16: There was no sensual pleasure involved in Christ’s birth and no vice in his life, so incarnation does not involve God in weakness. Birth and death are changes / movements in human existence to which God is subjected in the incarnation. Christ’s death does not involve weakness because, whereas the soul and body are separated by death, Christ reunited them in the resurrection.
Chapter 17: Nyssen addresses detractors. Patients don’t debate the terms of healing with physicians so we ought not do so with God. The eye of faith is required to grasp matters, although in the end it will be revealed to all.
Chapter 18: Though the eye of faith is required, there is still the witness of history. The flourishing of the church and the destruction of the Jewish temple argue for the truth of the incarnation.
Chapter 19: Nyssen finally begins directly addressing the question of Chapter 14. Human nature is healed by union with divine nature.
Chapter 20: God is defined by all excellent things, and especially by goodness. How do these fit with the incarnation? Nothing is more good than God’s acting to regain our allegiance, while God’s wisdom and skill are revealed in the economy as God does so. God’s wisdom and justice require special attention.
Chapter 21: Nyssen returns to his anthropology. Humanity is subject to change because it comes into existence. Human alteration is also necessary to distinguish humanity from God. Alteration can move either toward good or away from good (toward evil), and this movement is driven by the will which desires beauty but can be mistaken about what is beautiful. This is the situation from which we need saving, and God’s goodness / wisdom / justice are revealed in the salvific process.
Chapter 22: Justice pertains to the means by which God ransoms humanity.
Chapter 23: What would Satan take in exchange for humanity? Something better, which Christ reveals himself to be while his divinity remained hidden. That redemption was a matter of exchange exhibits God’s justice and the manner in which this was prosecuted reveals God’s wisdom.
Chapter 24: God’s wisdom hid Christ’s deity under his humanity, which made him like a baited fish-hood. In accepting the exchange, Satan inadvertently established the conditions necessary to break his own power by introducing divine life and goodness into the heart of human death and evil.
Chapter 25: The incarnation is not all that strange conceptually speaking because God is always present to everything, but he is uniquely present in the incarnation so that our nature might become divine.
Chapter 26: God skillfully combined justice and love. Justice is defined by fitting recompense, and it is fitting that the deceiver (Satan) was deceived. The approximation of divine goodness to human sin obliterates the latter, and this expulsion of evil restores us to the primal state in which we were created. This is done by means of God passing through all accidents of human life (and, though it is not stated here, by Christ acting virtuously therein).
Chapter 27: All aspects of human life are tainted by sin, and so all require healing. That is why God partook of all human life’s accidents (recapitulation). All creation is equally beneath God’s dignity, but doing good to those in need is not. The incarnation is therefore not foreign to God.
Chapter 28: God is separate from evil, but human nature and materiality are not evil as such. So, the incarnation is not inconceivable.
Chapter 29: Why did God wait so long to become incarnate? He waited for evil to become as extensive as possible so as to heal it as extensively as possible.
Chapter 30: Why is sin not now entirely removed from our existence? Sin is defeated and dead, but still in its death throes. Free will is part of this equation.
Chapter 31: God does not work through fiat or sheer omnipotence, but respects humanity’s free will – which God created. There is no virtue without free will, and there is no value to life without virtue.
Chapter 32: Some say it was needless for God to submit to death, but he had to because death is part of human existence (in the background is the logic of ‘what is not assumed is not redeemed’, see chapters 26 & 27). Christ’s birth was for the sake of his death since our nature needed lifting from death. Christ’s resurrection has implications for the whole human race. Mystagogy of the cross: the shape of the cross points in four directions, and represents the union of heaven (God) and earth (humanity) spanning from birth to death.