HYPOSTATIC UNION, GRACE OF

The incarnation of the son of god is the supreme gift or grace of God to man. From the 12th century, theologians have designated this aspect of the hypostatic union as "the grace of union" (gratia unionis ).

Historical. The New Testament frequently speaks of Christ as the manifestation or gift of God's graciousness toward sinful man, sometimes using the word χάρις (grace), e.g., Jn 1.14–17; Ti 2.11. For St. Augustine, the hypostatic union is the model of man's grace; just as Jesus did not merit to be the Christ, the unique and sinless Son of God, so men do not merit to be Christians, reborn, freed from sin (Praed. sanct. 15.30–31, Patrologia Latina 44:981–983; cf. Enchir. 36, Patrologia Latina 40:250). The Middle Ages in developing Augustine's teaching sought to safeguard the gratuity of the Incarnation without making Christ a merely adoptive son. Against Spanish adoptionism of the late 8th century, Alcuin (Adv. haer. Felic. 69; Patrologia Latina 101:116) insisted on distinguishing grace and adoption. In the 12th century, a frequent formula (attributed, without clear textual support, to both Ambrose and Augustine) was that the humanity or soul of Christ received by grace all that His divinity had by nature. Christ as man, though not an adoptive Son, was declared to be Son by grace and Son by union, in contrast with His being in His divinity Son by nature. Finally Peter Lombard (3 Sent. 10.2.67–69; Quaracchi 2.595–596) combined both expressions in the phrase "grace of union." Thirteenth-century theologians explored this gratia unionis and identified it variously as the Holy Spirit producing the union, as a created disposition for the union, as the hypostatic union itself, etc. St. Thomas Aquinas (Comp. theol. 214; cf. Summa theologiae 3a, 7, introd.; 8.5 ad 3) and others distinguished a threefold grace in Christ: grace of union, habitual grace, and grace of headship. In subsequent theology the grace of union was discussed primarily in connection with the substantial sanctity of Christ and was explained in accordance with various speculative theories of the hypostatic union. The two principal questions on which theologians continued to differ were the following: (1) Is the grace of union created or uncreated? (2) Does the grace of union sanctify the humanity of itself or only because it has habitual grace as consequence?

Systematic. The hypostatic union, as a gift proceeding from the gracious will of God communicating Himself substantially to man beyond the powers, exigencies, or merits of human nature, is the supreme grace. This grace of union may be termed uncreated or created accordingly as one regards the Divine Person of the word, who communicates Himself to His humanity, or the created reality of union in that humanity. Theologians commonly distinguish this substantial grace, which is identical with the hypostatic union, from Christ's habitual or sanctifying grace and His grace of headship, accidental graces that flow from the grace of union and are measured by it. Because of the grace of union, Christ's humanity is holy and sinless (see impeccability of christ), and the man Christ is the natural, not adoptive, Son of God. It is ultimately because of the grace of union that His habitual grace and virtues have a quasi-infinite perfection, and His salvific actions are intrinsically apt to sanctify all mankind, whose grace is incarnational and filial because it participates in the grace of union through the mediation of Christ's habitual grace and virtues as informing His saving action.

Bibliography: a. michel, Dictionnaire de théologie catholique, ed. a. vacant et al. (Paris 1903–50) 7.1:437–568. a. vugts, La Grâce d'union d'après S. Thomas d'Aquin: Essai historique et doctrinal (Tilburg 1946). j. rohof, La Sainteté substantielle du Christ dans la théologie scolastique: Histoire du problème (Fribourg 1952). se

[t. e. clarke]