The most important form of all Christian liturgy is the Mass. Within the setting of a Jewish Passover meal, the Lord instituted the Eucharistic sacrificial meal of the New Covenant. It was from this rite that the New Testament liturgy was born.
The Passover meal was a ritual. It called for certain foods, including bread and wine, as well as certain prayers and explanations. On the night before He died, Jesus took some of the unleavened bread, offered it to the Father, and said, “This is my body.” He gave His Body to the Apostles to eat. He took a cup of the Passover wine and said, “This is my blood, the blood of the new covenant.” He gave His Blood to the Apostles to drink. He told them, “Do this in remembrance of me.”
Obedient to Christ, the Church does what Christ did, in memory of Him. The worship of the Church and its whole inner life have always centered on the Eucharistic sacrifice, the Mass.