What is the Eucharist?
The Eucharist is the source and summit of the Christian life. The term “Eucharist” originates from the Greek word eucharistia, meaning thanksgiving.
In the celebration of the Eucharist, bread and wine become the Body and Blood of Jesus Christ through the power of the Holy Spirit and the instrumentality of the priest. The whole Christ is truly present -- body, blood, soul, and divinity -- under the appearances of bread and wine, the glorified Christ who rose from the dead. This is what the Church means when she speaks of the "Real Presence" of Christ in the Eucharist.
Where is the Eucharist mentioned in the Bible?
The Lord Jesus, on the night before he suffered on the cross, shared one last meal with his disciples. During this meal our Savior instituted the sacrament of his Body and Blood. He did this in order to perpetuate the sacrifice of the Cross throughout the ages and to entrust to the Church a memorial of his death and resurrection. The Institution of the Eucharist is written down in the four Gospels below:
John 6:22-59 (The Bread of Life Discourse)