The life of Jesus of Nazareth is a mystery, from conception to his ascension. In his passion, death, resurrection and glorification, the mystery of Jesus Christ is clarified and becomes the central core of the Christian faith. In the paschal mystery, the salvific plan of God was fulfilled once and for all with the redeeming death of his Son, Jesus Christ. Jesus conquered suffering, sin, and death and opened a path of full life for men. First, in the Old Testament, we have the term pesah (passage) for the Easter feast, and then in the New Testament the Christian communities from the 1st to the 3rd century came to understand Easter as the mystery of Christ. This mystery includes all of salvation history, which has its culmination in JesusChrist, his incarnation, his death, his glorious resurrection and then in the joyful waiting for his return. The communities remembered the immolation of Jesus on the cross, the primordial saving act. The crucifixion of Christ was understood, by the first Christians, as the beginning of his glorification. This continuous and progressive historical line of God s plan for humanity and the biblical foundation of mystery are the bases on which the concept of the Paschal Mystery was elaborated in the second century. Patristic theology, between the 3rd and 4th centuries, reflects the paschal mystery of Christ with a focus on the dimensions: salvific, ecclesial and sacramental history. Years later, a liturgical movement takes up the theology based on the biblical-patristic sources and gives fontal vigor to the liturgy. Pius XII slowly incorporates the theology of mystery, thought up by the liturgical movement, into pre-conciliar documents. In this progressive movement, the liturgical theology of the paschal mystery is concretized in the dogmatic constitution Sacrosanctum Concilium, which establishes the paschal mystery as the summit and source of the liturgy.