Final answer:
The rite of initiation into Christianity viewed as a participation in Jesus' victory over death is Baptism, which represents purification and admission to the Christian faith.
Step-by-step explanation:
The rite of initiation into Christianity that is considered a participation in Jesus' victory over death is Baptism. Baptism is a sacrament in Christianity that symbolizes purification and admission into the Christian community. It is often carried out on newborn children due to the belief in original sin, with the notion that baptism clears this sin and ensures the possibility of entering heaven, which was especially poignant in medieval times due to high infant mortality rates. Moreover, baptism is also considered to represent the individual's death to sin and rebirth into a new life in Christ.
Baptism is rooted in Jewish purificatory rituals rather than mystery religions and serves as a critical ceremony within Christianity, defining a transition in spiritual life and status, aligning with Arnold van Gennep's model of rites of passage which includes separation, transition, and incorporation into a new social structure.