1. During his earthly life, Jesus gathered a group of men, the Twelve, to be the foundation of the Church. He formed and prepared them to continue his work. At the Last Supper, he carried out the very action by whose choice he also freely accepted the suffering and death which followed the next day—namely, the action of giving himself to his chosen band in the appearance of bread and wine for humankind. Moreover, he directed the Twelve to do the same thing on his behalf (22‑G).
2. Included within Jesus’ single act of self-oblation are the subsequent actions performed to fulfill his command by the apostles, their successors, and their successors’ priestly assistants. Thus, in the Eucharist—and, by association with the Eucharist, in all the other sacraments—Jesus’ redemptive act is made present to us, available for our cooperation and effective for our sanctification (see S.t., 3, q. 65, a. 3; q. 78, a. 1; q. 83, a. 1).
3. As extensions into the present of Jesus’ unique redemptive act, the sacraments have all its complexity. They reveal and communicate the divine life which they signify, while at the same time responding to it with appropriate human worship (see S.t., 3, q. 61, a. 1; q. 62, a. 1). Furthermore, these two aspects mutually include each other.
4. As revelatory, the sacraments have the complexity of every revelatory sign: They involve mutually complementary words and deeds. Likewise, as acts of worship, they involve the complexity of all such acts: They involve mutually complementary prayers and rituals of worship (see S.t., 3, q. 60, aa. 5–7).
5. As one can imagine that God could have redeemed and deified human beings without the Incarnate Word (that is, without any really adequate creaturely cooperation), so one can imagine that Jesus could offer us the benefits of his redemptive work without any adequate cooperation on our part. He could, for example, simply have extended forgiveness and a share in divine life to those who would accept them, perhaps without their even knowing explicitly what they were receiving (as in fact seems now to be the case with nonbelievers who are saved). Or he might have arranged that news of what he had done be proclaimed abroad, with the provision that those who believed and trusted in him would passively receive the benefits of his work (this is the classic Protestant conception).
6. In line, however, with the basic reason for the Incarnation itself—the ennobling of humankind and, thereby, the greater glory of God—Jesus arranged from the beginning to make sinful men and women his co-workers in their own redemption and the redemption of their brothers and sisters.3 To make this cooperative work possible in a way wholly suited to our needs and capacities, he instituted the sacraments (see S.t., 3, q. 46, a. 3; sup., q. 34, a. 1).
The life of Jesus as the principle of Christian life was treated in chapters twenty-two and twenty-three. The present discussion relates the sacraments to the redemptive act of Jesus which is their principle.
To redeem humankind and confer a share in divine life on created persons essentially is work only God can do. Redemption demands re-creation; deification can occur only by a divine begetting. However, God did not wish to redeem us and deify us without our free consent and willing cooperation. He is trying to bring us up to the dignity of mature children of God, not make puppets of us.
His problem was how to make human persons able to cooperate in their own redemption and deification. God’s solution to this problem is the Incarnation, the human acts of Jesus, culminating in his self-oblation on the cross, and the divine response of the resurrection and glorification of Jesus. Jesus in glory indissolubly unites in himself the whole power for good, the total capacity to achieve fulfillment, of creator and creature. His potentiality is for the totality of goodness which God wills. He is in process of realizing this capacity. Its ultimate realization will be the fulfillment of everything in our Lord Jesus (19‑B).
The new covenant principally is Jesus in glory. What he does, the Father and the Spirit also do; the divine persons are perfectly unanimous—that is, of one mind and purpose. The forgiveness of sin and the begetting of created persons to divine life is at our disposal, not as if re-creation and divinization were acts within creaturely power, but because we are united with our Lord, who in glory acts both as God and as man. Through him God has put himself at the disposal of his creatures (see S.t., 3, q. 62, aa. 1, 3, 5).
The human life of Jesus centers in his personal commitment to do the Father’s will, and specifically to carry out his personal vocation. Replacing Adam who separated humankind from God, Jesus reconciles humankind to God, to the extent that human action can do so. In doing this, he accomplishes two things at once. First, he provides a community-forming human act—thus a principle homogeneous to us, something we can “plug into.” In this respect, his human life is the revelatory and communicative work of the Word Incarnate. But second, he acts toward God precisely as a human being, in his situation, should act. He does all in his human power to be a perfect Son.
Consequently, the divine act by which he is raised from the dead and established in glory as Lord of the universe is not imposed on creation willy-nilly. The Word Incarnate has freely consented to and fully cooperated with God’s plan. He has merited his role as Lord in power (see Rom 1.4). By accomplishing redemption in this way, God enriches creation and wonderfully achieves his glory, which is the expression of his goodness. Had God redeemed and divinized us without the action of Jesus, creation would be so much the poorer, and the manifestation of God’s goodness the less (see S.c.g., 3, 69).
Thus, the glory of the Word Incarnate detracts nothing from the Father and the Spirit, but rather equally glorifies all three persons. The same will be true of our glory. Hence, there is no need to be anxious when sacramental doctrine attributes much to the work of created persons. To attribute much to ourselves is to attribute more to God, for we are and have nothing but sin which is not his gift.
3. A helpful treatment of the Catholic conception of sacramentality: Karl Adam, The Spirit of Catholicism, trans. Justin McCann, O.S.B. (New York: Macmillan, 1931), esp. 176–92.