The One Christ: St. Augustine's Theology of Deification
200 Ecclesial Reception of the Divine Life implies a perfect unity of divinity and humanity unique to the incarnate Son. For example, we hear how, "The truth is that he who is the only Son of God by nature, not by grace, took man (suscepit hominem) to himself by grace into such a unity of person that he was also the Son of Man."39 This manner of union is reserved for the incarnate Son alone, for only he can be said to assume a once alien nature to himself. What distinguishes the unique unity of divinity and humanity in Christ from the manner of how the elect are made divine, is that the Son assumes humanity to himself in a way essentially different from how humans appropriate divinity. In other words, while the Son's union with humanity is explained as a susceptio, humanity's "contact" with divinity is explained in terms of, most often, participatio.
Many of these terms and images come into focus in a passage from the end of Augustine's well-known letter to Dardanus on the divine presence, which we treated in part in the preceding chapter. In explaining the essential difference between how Christ is divine and how divinity dwells in the saints, Augustine writes:
Or, apart from the fact that the fullness of divinity dwells in that body as in a temple, is there another difference between that head and the excellence of any member? There clearly is, because the singular assumption of that man formed one person with the Word. For no saint could or can or will it be able to be said, And the Word became flesh (John 1:14). No saint by any excellence of grace has received the title "the Only-Begotten" in the same way that he who was the very Word of God before all ages bears this same title after assuming the man. . . . For who would be so sacrilegious as to dare to say that some soul could bring it about by the merit of his free choice that he be another Christ?40
39. ench. 11.36; Harbert, Enchiridion (I/8), 296: "Veritas quippe ipsa, unigenitus dei filius non gratia sed natura, gratia suscepit hominem tanta unitate personae ut idem ipse esset etiam hominis filius."; CCL 46.70.
40. ep. 187.13.40; Teske, Letters (II/2), 249: "an etiam praeter hoc quod, tamquam in templo, in illo corpore habitat omnis plenitudo diuinitatis, est aliud, quod intersit