Objection 1. It would seem that Christ's Resurrection is not the cause of the resurrection of our bodies, because, given a sufficient cause, the effect must follow of necessity. If, then, Christ's Resurrection be the sufficient cause of the resurrection of our bodies, then all the dead should have risen again as soon as He rose.
Objection 2. Further, Divine justice is the cause of the resurrection of the dead, so that the body may be rewarded or punished together with the soul, since they shared in merit or sin, as Dionysius says (Eccles. Hier. vii) and Damascene (De Fide Orth. iv). But God's justice must necessarily be accomplished, even if Christ had not risen. Therefore the dead would rise again even though Christ did not. Consequently Christ's Resurrection is not the cause of the resurrection of our bodies.
Objection 3. Further, if Christ's Resurrection be the cause of the resurrection of our bodies, it would be either the exemplar, or the efficient, or the meritorious cause. Now it is not the exemplar cause; because it is God who will bring about the resurrection of our bodies, according to John 5:21: "The Father raiseth up the dead": and God has no need to look at any exemplar cause outside Himself. In like manner it is not the efficient cause; because an efficient cause acts only through contact, whether spiritual or corporeal. Now it is evident that Christ's Resurrection has no corporeal contact with the dead who shall rise again, owing to distance of time and place; and similarly it has no spiritual contact, which is through faith and charity, because even unbelievers and sinners shall rise again. Nor again is it the meritorious cause, because when Christ rose He was no longer a wayfarer, and consequently not in a state of merit. Therefore, Christ's Resurrection does not appear to be in any way the cause of ours.
Objection 4. Further, since death is the privation of life, then to destroy death seems to be nothing else than to bring life back again; and this is resurrection. But "by dying, Christ destroyed our death" [Preface of Mass in Paschal Time]. Consequently, Christ's death, not His Resurrection, is the cause of our resurrection.
On the contrary, on 1 Corinthians 15:12: "Now if Christ be preached, that He rose again from the dead," the gloss says: "Who is the efficient cause of our resurrection."
I answer that, As stated in 2 Metaphysics, text 4: "Whatever is first in any order, is the cause of all that come after it." But Christ's Resurrection was the first in the order of our resurrection, as is evident from what was said above (Question 53, Article 3). Hence Christ's Resurrection must be the cause of ours: and this is what the Apostle says (1 Corinthians 15:20-21): "Christ is risen from the dead, the first-fruits of them that sleep; for by a man came death, and by a man the resurrection of the dead."
And this is reasonable. Because the principle of human life-giving is the Word of God, of whom it is said (Psalm 35:10): "With Thee is the fountain of life": hence He Himself says (John 5:21): "As the Father raiseth up the dead, and giveth life; so the Son also giveth life to whom He will." Now the divinely established natural order is that every cause operates first upon what is nearest to it, and through it upon others which are more remote; just as fire first heats the nearest air, and through it it heats bodies that are further off: and God Himself first enlightens those substances which are closer to Him, and through them others that are more remote, as Dionysius says (Coel. Hier. xiii). Consequently, the Word of God first bestows immortal life upon that body which is naturally united with Himself, and through it works the resurrection in all other bodies.
Reply to Objection 1. As was stated above, Christ's Resurrection is the cause of ours through the power of the united Word, who operates according to His will. And consequently, it is not necessary for the effect to follow at once, but according as the Word of God disposes, namely, that first of all we be conformed to the suffering and dying Christ in this suffering and mortal life; and afterwards may come to share in the likeness of His Resurrection.
Reply to Objection 2. God's justice is the first cause of our resurrection, whereas Christ's Resurrection is the secondary, and as it were the instrumental cause. But although the power of the principal cause is not restricted to one instrument determinately, nevertheless since it works through this instrument, such instrument causes the effect. So, then, the Divine justice in itself is not tied down to Christ's Resurrection as a means of bringing about our resurrection: because God could deliver us in some other way than through Christ's Passion and Resurrection, as already stated (46, 2). But having once decreed to deliver us in this way, it is evident that Christ's Resurrection is the cause of ours.
Reply to Objection 3. Properly speaking, Christ's Resurrection is not the meritorious cause, but the efficient and exemplar cause of our resurrection. It is the efficient cause, inasmuch as Christ's humanity, according to which He rose again, is as it were the instrument of His Godhead, and works by Its power, as stated above (13, 2,3). And therefore, just as all other things which Christ did and endured in His humanity are profitable to our salvation through the power of the Godhead, as already stated (48, 6), so also is Christ's Resurrection the efficient cause of ours, through the Divine power whose office it is to quicken the dead; and this power by its presence is in touch with all places and times; and such virtual contact suffices for its efficiency. And since, as was stated above (ad 2), the primary cause of human resurrection is the Divine justice, from which Christ has "the power of passing judgment, because He is the Son of Man" (John 5:27); the efficient power of His Resurrection extends to the good and wicked alike, who are subject to His judgment.
But just as the Resurrection of Christ's body, through its personal union with the Word, is first in point of time, so also is it first in dignity and perfection; as the gloss says on 1 Corinthians 15:20-23. But whatever is most perfect is always the exemplar, which the less perfect copies according to its mode; consequently Christ's Resurrection is the exemplar of ours. And this is necessary, not on the part of Him who rose again, who needs no exemplar, but on the part of them who are raised up, who must be likened to that Resurrection, according to Philippians 3:21: "He will reform the body of our lowness, made like to the body of His glory." Now although the efficiency of Christ's Resurrection extends to the resurrection of the good and wicked alike, still its exemplarity extends properly only to the just, who are made conformable with His Sonship, according to Romans 8:29.
Reply to Objection 4. Considered on the part of their efficiency, which is dependent on the Divine power, both Christ's death and His Resurrection are the cause both of the destruction of death and of the renewal of life: but considered as exemplar causes, Christ's death--by which He withdrew from mortal life--is the cause of the destruction of our death; while His Resurrection, whereby He inaugurated immortal life, is the cause of the repairing of our life. But Christ's Passion is furthermore a meritorious cause, as stated above (Question 48, Article 1).
Source: Summa Theologica (New Advent)