Book Review: Aaron Riches, Ecce Homo: On the Divine Unity of Christ

Bart Byl
9 min readDec 24, 2022

Aaron Riches. Ecce Homo: On the Divine Unity of Christ. Grand Rapids, MI: 2016. xxi + 279 pp.

Ecce Homo offers a fierce resistance against any kind of separatio of the single theandric Christ, especially the modern tendency to divide the Jesus of history from the Christ of faith. Although his Mariological conclusion will be off-putting to readers who are not traditional Catholics, Riches’s closely argued historical theology reveals the soteriological possibilities inherent in the hypostatic union.

The volumes in the Interventions series, according to General Editor Conor Cunningham, aim to “seek and perform tactical interventions in [theological] debates in a matter that problematizes the accepted terms of such debates.” Aaron Riches’s contribution is to explore, based on a close reading of patristic and medieval Christology, “the depths implicit in the confession of ‘one Lord Jesus Christ,” as Rowan Williams put it in his foreword (xv). What does it mean to declare that the divine and human natures have fused together in the hypostatic union? And what implications does the unity of Christ have for Christian theology?

The task Riches sets for himself is to “free this unity both from dualistic distortions of divinity and humanity that would divide the one Christ, and from an exclusivist solus Christus that would remove him from the experience and participative possibilities of everyday life” (xvii). Riches takes particular aim at homo assumptus Christologies “according to which the Logos is said to have assumed a human being” (2). Christ’s human nature has no existence apart from union with the divine Logos. Riches charges modern theology with neglecting the traditional doctrine of communicatio idiomatum, interpenetrating communication of properties that maintains the “unbearable tension between the incompatible attributes of divinity and humanity” (4). The centrifugal force of the two natures must be balanced by the centripetal force of union.

Riches begins his story in the fourth century. Alarmed by the suggestion that the impassible God had been born of a woman and suffered on the cross, Nestorius had emphasised separatio to such a degree that the unity of the natures was compromised (5). His dualism was roundly condemned by Cyril of Alexandria, who asserted “one incarnate nature of the Word”. Although the term mia physis appears to contradict the subsequent Chalcedonian definition of the two natures, Riches argues that the conflict is only apparent; Cyril intends no blurring of the natures and his formula “is basically convertible with the doctrine of the hypostatic union” (6). As Riches explores in his chapter on “The Humanity of Christ,” Christology is always enmeshed with soteriology. If it was not the divine Logos who suffered on the cross, but only the human whom he assumed, then salvation comes from below, not from above: humanity can save itself. Thus, as Charles Gore famously remarked, “The Nestorian Christ is a fitting savior of Pelagian man” (7). But it is only in the hypostatic union that human nature is truly glorified, for the Incarnation is the beginning of humanity’s deification (8).

The Council of Chalcedon in 451 marked a milestone in Christology. As Riches observes, the Chalcedonian Formula carefully balances difference and unity with the four adverbs used to describe the hypostatic union: inconfuse and immutabiliter (without confusion and without change) preserve the distinction of natures, while indivise and inseparabiliter Ibid., without division and without separation) maintain their unity in the one Lord Jesus Christ (9). Riches notes, perceptively, “the result of the Chalcedonian formulation was to realize very clearly that ‘the proximity of the divine’ does not threaten or compromise ‘the integrity of the human,’ but in fact establishes it” (61).

But to what degree did does Chalcedon reflect Cyrillian Christology? For the miaphysites, the Council’s diophysite formula was a betrayal of Cyril’s legacy, a conviction held to this day among the Oriental Orthodox churches. But doubts over whether Chalcedon fully vindicated Cyril have come from the modern heirs of Chalcedon as well. In the last century, for example, Karl Rahner argued for a furthering of Chalcedon that, as Riches puts it, was “based in the presupposition that the aim and key achievement of the Definitio was to carefully balance Nestorian ‘separation’ against Cyrillian ‘union’” (73). To renew the Chalcedonian impulse, Rahner proposed, the Church needs to recover the insights of Nestorius, Theodore, and the rest of the ‘Antiochene School’ in order to correct unhealthy Cyrillian excesses. But as Riches demonstrate, this fails for two reasons: as Louth, Behr, and others have demonstrated, the idea that there were two distinct ‘schools’ in Antioch and Alexandria is a myth; moreover, the Acts of Chalcedon demonstrate the bishops saw themselves squarely in the tradition of “blessed Cyril” (75).

In Part Two, “The Synergy of Christ,” Riches turns to the aftermath of Chalcedon in the following centuries, devoting most of his attention to Maximus the Confessor and the monothelite controversy of the seventh century. Following Gregory of Nazianzus’s dictum, “that which is not assumed is not healed,” Maximus argued strenuously (and at terrible personal cost) that Christ possessed a human will as well as a divine will. He carefully specified, though, that Christ did not possess the postlapsarian “gnomic will” by which humans deliberate over rather than naturally intuit the good. This distinction is vital, as Riches points out, because to confess a gnomic will in Christ “would be to admit a subjective centre in Jesus in addition to the divine filiation of the Son” (137). All that Christ wills humanly, Maximus concludes, is in “perfect harmony and concurrence” with the will of God (138). The soteriological implications of this subtle distinction are profound. In the neo-Apollinarist scheme of the monothelites, union with God obliterates the human will. But for Maximus, the human and divine exist within the one Christ in a noncompetitive, synergistic relationship. This is demonstrated supremely in Christ’s prayer in Gethsemane, where humanity’s fallen will finds salvation precisely through Christ’s human will operating in harmonious synergy with the divine will. “If he conquered as God, to us it is nothing,” Cyril had written perceptively, “but if he conquered as man we conquered in him” (148).

Riches moves onto the medieval Catholic reception of Cyril and Maximus in Part Three, “The Existence of Christ”. He focuses on Thomas Aquinas, who conducted his own theology of retrieval in the thirteenth century, resourcing Cyril and John of Damascus’s The Orthodox Faith to correct a drift toward the crypto-Nestorian homo assumptus Christologies of his medieval Catholic predecessors. Thomas’s Christology thus “is truly a Latin work across the Great Schism” (156). Thomas robustly affirms the single divine essence of the incarnate Word. Yet “the humanity of Christ is the instrument of the divinity,” as Thomas wrote. The union between Creator and creature is asymmetrical. As Riches summarises, “the human nature contributes nothing to the existence of the Logos, and is nothing apart from the Logos” (165–66). For Thomas, following Maximus, the agony in the garden is the epitome of theandric action. Although Christ as a human being naturally recoiled from pain and death, there was, properly speaking, no conflict between his human and divine wills, which agreed in pursuing the higher goal of humanity’s salvation through the cross. Gethsemane thus serves as the highest example of the human will finding its true purpose in the love of God. “Love is indeed ‘ecstasy,’” as Benedict XVI writes in Deus caritas est, “a journey, an ongoing exodus out of the closed inward-looking self towards its liberation through self-giving, and thus towards authentic self-discovery and indeed the discovery of God” (quoted on 191).

At the cross, the divine Son suffers in his humanity. Not only does Christ take on himself all human sin and suffering, according to Thomas, he does so while still enjoying the bliss of the beatific vision. Understandably, modern interpreters of Aquinas have wondered how he can avoid the charge of docetism. We find ourselves on the horns of a dilemma: if the Logos lost the beatific vision, the Trinity was ruptured. But if the Son was enjoying the bliss of filial communion, how could he be said to truly experience pain? Here, again, we find ourselves confronting the paradox of the suffering of the impassible God. Riches suggests that the suffering of Christ is actually rooted in his communion with the Father: his grief is somehow the result of the purity of divine fellowship confronting the brokenness of human sin. Ibid., Riches is less assured in this section of the book; explanations of the mysteries of the hypostatic union during the Crucifixion can be tentative at best.) He cites the 1951 ‘Pian limit’ of Pius XII’s Sempiternus Rex against Duns Scotus’s modern and more speculative heirs who, in their eagerness to emphasise the full humanity of Christ, have posited a homo assumptus Christology. “Whatever human ‘psychology’ Jesus may possess,” Riches avers, “it cannot imply a human ‘psychology’ that operates alongside the persona divina as a second subjective center” (218). The Logos did not assume a human person; he became incarnate and assumed a human nature — received, Riches emphasizes, from his human mother. “Mary ensures that the humanity of Christ is not an abstraction” (225).

A final coda is entitled, “The Communion of Jesus and Mary.” In Matthew 16, after Peter confesses Jesus as the Christ, he resists the Lord’s commitment to suffer and die. But it will be precisely at the cross where the identity of Jesus as the God-man is most fully manifested. The church confesses one Saviour: the Crucified Lord. In the words of the tenth anathema of Constantinople II: “He who was crucified in the flesh, our Lord Jesus Christ, is true God, Lord of glory, and one of the Holy Trinity” (239). Riches goes on to argue that “the mystical union with Christ to which humanity is called in the Church finds its perfect expression in Mary, who, filled with a grace than unites her uniquely to her Son, inhabits and follows the cruciform path of Jesus in an exemplary and singular fashion” (241). At the Cross Mary surrenders her Son, and experiences “a state of divine abandonment in which she can no longer claim to be the ‘Mother of God’”. Thus, Riches argues flatly, “there can be no argument about co-redemption. As a descriptive term of what actually happened on Calvary, it is a fact” (246).

In Ecce Homo, Riches offers a closely argued case for affirming the unity of the one Lord Jesus Christ, buttressed by careful attention to the historical development of doctrine. His work is a dedicated act of resourcement, one that does not pit the Church Fathers against the medieval scholastics, but that champions Thomas Aquinas himself as resourcing Cyril and the ecumenical councils to call the Church back to the paths of Christological orthodoxy.

Riches has been a faculty member of various Roman Catholic institutions, and writes, self-consciously, as a faithful son of the Church. He is no iconoclast, challenging the hierarchy to adjust the faith to the demands of the (post-)modern world. He upholds the tradition against all comers: not as a mere reactionary, but as one convinced that the great Doctors and Councils of the Church offer great insight to those willing to toil in history. So although Riches is clearly unhappy even with Karl Rahner’s desire to creatively extend the insights of Chalcedon, this is because he believes Rahner is compromising the integrity of the Church’s Christology, not because he thinks doctrine must be preserved in stasis.

Rowan Williams’s foreword notwithstanding, Riches’s approach will limit the helpfulness of this book to those in other Christian traditions. The sole Protestant author Riches engages is Karl Barth, in his discussion on enhypostatos (107–111). Perhaps it is too much to ask for insight on the communicatio idiomatum as it relates to the sixteenth-century Lutheran-Reformed Eucharistic controversy, but what of Moltmann’s argument that Jesus as the crucified God justifies abandoning the classic doctrine of God’s impassibility? Even more alienating for a Protestant (however guilty we are for neglecting the Mother of God) is Riches’s fierce argument for Mary as co-Redemptrix. Not only has this medieval doctrine never found official support from the Magisterium (Pope Francis has registered his opposition to the title), but it seems a particularly ill-fitting climax to a book on Christology. Mary’s title as Theotokos is the beginning of Christological debate, but surely not its summit.

Yet, for all that, Riches’s historical arguments are robust and his theological reflections on the unity of Christ are rich and suggestive. One only wishes he had gathered up the manifold implications of the unity of Christ for the salvation of humanity. As he hints throughout the volume, the hypostatic union is the sign and earnest of the deification of humanity, a future in which our nature is not destroyed but finds its true glory freedom in God. Ecco Homo leaves those implications to the reader, but anyone who attends carefully to Riches’s arguments cannot fail to see them.



Bart Byl

Th.M. student at Regent College. Canadian in Georgia. 🇨🇦🇬🇪