“By the grace of God” Jesus tasted death “for every one”. In his plan of salvation, God ordained that his Son should not only “die for our sins” but should also “taste death”, experience the condition of death, the separation of his soul from his body, between the time he expired on the cross and the time he was raised from the dead. the state of the dead Christ is the mystery of the tomb and the descent into hell. It is the mystery of Holy Saturday, when Christ, lying in the tomb, reveals God’s great sabbath rest after the fulfilment of man’s salvation, which brings peace to the whole universe.
Christ’s stay in the tomb constitutes the real link between his passible state before Easter and his glorious and risen state today. the same person of the “Living One” can say, “I died, and behold I am alive for evermore”:
God [the Son] did not impede death from separating his soul from his body according to the necessary order of nature, but has reunited them to one another in the Resurrection, so that he himself might be, in his person, the meeting point for death and life, by arresting in himself the decomposition of nature produced by death and so becoming the source of reunion for the separated parts.
Since the “Author of life” who was killed is the same “living one [who has] risen”, The divine person of the Son of God necessarily continued to possess his human soul and body, separated from each other by death:
By the fact that at Chnst’s death his soul was separated from his flesh, his one person is not itself divided into two persons; for the human body and soul of Christ have existed in the same way from the beginning of his earthly existence, in the divine person of the Word; and in death, although separated from each other, both remained with one and the same person of the Word.
Christ’s death was a real death in that it put an end to his earthly human existence. But because of the union his body retained with the person of the Son, his was not a mortal corpse like others, for “divine power preserved Christ’s body from corruption.” Both of these statements can be said of Christ: “He was cut off out of the land of the living”,and “My flesh will dwell in hope. For you will not abandon my soul to Hades, nor let your Holy One see corruption.”Jesus’ Resurrection “on the third day” was the proof of this, for bodily decay was held to begin on the fourth day after death.
Baptism, the original and full sign of which is immersion, efficaciously signifies the descent into the tomb by the Christian who dies to sin with Christ in order to live a new life. “We were buried therefore with him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.”
From the Catechism of the Catholic Church 624-628
From the Catechism of the Catholic Church