1. The revelation of the mystery of the fullness of Jesus clarifies how God is actually bringing about the communication of his goodness which is his purpose in creating: the plan “to unite all things in him [Christ], things in heaven and things on earth” (Eph 1.10). God’s glory, the self-manifestation which he wills, is not merely comprised of many different creatures; the whole has unity, the unity of the Lord Jesus. All else will find its proper place in Jesus’ fullness.4 Since he is both God and man, the fulfillment of all things in him unites God’s uncreated perfection with his created glory. The remainder of this question considers the complex reality of the fulfillment of everything in Jesus from several points of view.
In the Old Testament it is frequently said that God fills the earth, Jerusalem, and the temple. Without becoming mixed with his creation, God’s glory, name, and presence fill and fulfill his creatures. With the Incarnation, God is present in a new way: “For in him [Christ] the whole fulness of deity dwells bodily” (Col 2.9). Jesus holds the first place in God’s plan (see Col 1.15–20). Because he is both God and man, the Lord Jesus can integrate all of reality (see AG 3).
2. The good which God communicates in Jesus is himself. Insofar as he is God, Jesus unites his fellow human beings with the Father: “The glory which you have given me I have given to them, that they may be one even as we are one, I in them and you in me, that they may become perfectly one” (Jn 17.22–23; cf. S.t., 1, q. 43, aa. 1–3, 6). Insofar as he is man, Jesus achieves his human fulfillment by living a perfect human life in which God’s goodness is manifested in a unique way: “I glorified you on earth, having accomplished the work which you gave me to do” (Jn 17.4). God crowns Jesus’ holy life with its creaturely fulfillment by raising Jesus from the dead (see 1 Cor 15.20–28; Heb 4.5–10).
3. Insofar as he is God, Jesus communicates to us a share in his divine fullness (see Jn 1.16). Insofar as he is man, he is “the first-born of all creation” (Col 1.15) and is completed by creation united under his headship (see Eph 1.9–10, 22–23; LG 7).5 The whole reality of creator and creation thus comes to harmonious unity in the Lord Jesus; absolute fullness resides in him: “It pleased God to make absolute fullness reside in him and, by means of him, to reconcile everything in his person, both on earth and in the heavens making peace through the blood of his cross” (Col 1.19–20; NAB).6
4. Those who love God find their own fulfillment in the fellowship of everlasting life in Jesus. Everlasting life includes both a share in his divinity and in the creaturely fulfillment of his resurrection. Everlasting life is the ultimate end of human persons. Christians share by baptism in Jesus’ divinity and by the Eucharist in his resurrection life. Hence, although the everlasting life of Christians will be perfected later, they begin to attain their ultimate end even now (see Jn 1.12–13; 3.5; 6.47, 54; Rom 8.14–19; Eph 2.6–7; Col 1.9–23; 3.1–4; 1 Jn 3.1–2).7
5. Jesus’ fullness extends through the blessed to all things: “For all things are yours . . and you are Christ’s; and Christ is God’s” (1 Cor 3.21, 23). Christ’s fullness extends not only to humankind but also to the rest of creation. Because the world is “intimately related to man and achieves its purpose through him” (LG 48), it will share in human fulfillment, for which it now waits (see Rom 8.19; cf. S.t., sup., q. 91, a. 1).
6. The fullness of deity present in Jesus will be communicated, “that God may be everything to every one” (1 Cor 15.28). Yet, contrary to a pantheist conception, the created reality of human beings and other creatures will not be swallowed up in God. Creatures will remain creatures. Created persons sharing in Jesus’ fullness will know their creator, not be absorbed by him (see 1 Cor 13.12). The heaven in which they will find fulfillment is a city, that is, a fellowship (see Heb 12.22–24).
Jesus entered the heavenly sanctuary, not with the blood of an animal sacrifice, “but his own blood, thus securing an eternal redemption” (Heb 9.12). By Jesus’ resurrection, the kingdom of God—the communion of truth and life, of justice, love, and peace—is established. Admission is free for the asking; one need only accept it as a child accepts a gift (see Mk 10.15; Lk 18.17). The only thing necessary is communion with Jesus (see Lk 10.38–42). The power to become children of God and to share in the fullness of life present in Jesus is given to believers in him (see Jn 1.10–16). “He who believes has eternal life” (Jn 6.47).
4. A helpful introduction to the idea of the fullness of Jesus (pleroma Christi): George T. Montague, S.M., The Living Thought of Saint Paul: An Introduction to Pauline Theology (Milwaukee: Bruce, 1966), 182–203.
5. For indications of support in the Fathers for an eschatology along the lines sketched in this question and especially for support of the present point, see Georges Florovsky, “Eschatology in the Patristic Age: An Introduction,” Greek Orthodox Theological Review, 2 (1956), 27–40, esp. 30. For a systematic theological development of this eschatology: Bertrand de Margerie, S.J., Christ for the World: The Heart of the Lamb: A Treatise on Christology, trans. Malachy Carroll (Chicago: Franciscan Herald Press, 1974), esp. 238–52, 275–300 (where the idea of Church as coredeeming spouse is developed), 435–42, 486–507. Note the statement (492) that the “growth of the Church, the Body of Christ, signifies in the last analysis that Christ grows through it. Incomplete, in a sense, He grows toward His full eschatological stature . . ..”
6. The theological point made here depends upon reading Ephesians 1.23 as an affirmation that the Church somehow fulfills or completes Christ. Unfortunately, this verse is one of the most disputed in the New Testament. For a concise summary of possible interpretations and argument favorable to the one I accept: Roy Yates, “A Re-examination of Ephesians 1.23,” The Expository Times, 83 (1972), 146–51. In classic studies, J. Armitage Robinson laid out the argument for this interpretation and invoked in its favor the authority of all but one of the ancient translations of the Bible and the comments of three Fathers (Chrysostom, Origen, and Jerome): “The Church as the Fulfilment of the Christ: A Note on Ephesians I.23,” The Expositor, 7 (1898), 241–59; St. Paul’s Epistle to the Ephesians, 2d ed. (London: Macmillan, 1922), 42–45, 87–89, 100–101, 152, 255–59. The most extensive commentary by a Catholic exegete contains much useful background: A. Feuillet, P.S.S., “L’Eglise plérôme du Christ d’après Ephés., I.23,” Nouvelle Revue Théologique, 78 (1956), 449–72, 593–610; he argues convincingly that the concept of pleroma used by the author of Ephesians arises from the Old Testament rather than from pagan thought, but does not accept my reading of Ephesians 1.23. The most extensive commentary by a Protestant exegete: Marcus Barth, Ephesians, Anchor Bible, 34 and 34a (Garden City, N.Y.: Doubleday, 1974), 153–59, 192–210; cf. 440–41, 484–96. Barth recognizes the argument for the interpretation I prefer (see esp. 206, n. 324), but rejects it on theological grounds (which are countered in 23‑E, below, with accompanying notes). However, an exegesis fully in harmony with Catholic theological presuppositions (which does not hesitate to consider pleroma as all-inclusive community nor to think Jesus as man to be fulfilled by his members) is my chief source: Pierre Benoît, O.P., Jesus and the Gospel, vol. 2, trans. Benet Weatherhead (London: Darton, Longman and Todd, 1974), 51–92, esp. 84–91. Louis Bouyer, The Church of God: Body of Christ and Temple of the Spirit, trans. Charles Underhill Quinn (Chicago: Franciscan Herald Press, 1982), 252–57. See also George A. Maloney, S.J., The Cosmic Christ: From Paul to Teilhard (New York: Sheed and Ward, 1968), 26–36 and 60–68. For a theological development of Benoît’s view: Yves Congar, O.P., Jesus Christ, trans. Luke O’Neill (New York: Herder and Herder, 1966), 131–44.
7. See Bonaventura Mariani, O.F.M., “Il Nuovo Testamento e il Fine Ultimo dell’Uomo sulla Terra,” Divinitas, 20 (1976), 282–312. If it sounds odd to say that Christians really begin to attain their ultimate end in this life, this is because the theology of happiness formulated under Neoplatonic influence chiefly by St. Augustine overlooked or misconstrued the evidence of the New Testament on this question and located the ultimate end of human persons exclusively in the vision of God after death (see 34‑A).