As God gives detailed instructions to Moses concerning how the Passover is to be observed, a foreshadowing of the Eucharist comes into focus. The two principle elements to which our attention is drawn are the blood of the lamb that is placed on the doorposts and the unleavened bread which the people consume. At the Passover Jesus took the unleavened bread and said, “This is my body” and He took the cup of wine and said, “This is my blood” (Mt 26:26-28).
It is fascinating that even the details of the Passover connect us to Christ and the Eucharist. For example the Lord directed Moses that the blood is to be applied to the doorpost with a hyssop branch. Vinegar was offered to Jesus on a hyssop branch as He shed His blood on the cross for the sins of the world (Jn 19:29). It is His blood of the New Covenant that we receive by faith at Holy Communion.
It is especially emphasized that the bread must be unleavened in part because leaven is used in the Bible as a symbol for sin (I Cor 5:6-8). Jesus who was born in Bethlehem (beth = house; lechem = bread; = house of bread) referred to Himself as the Bread of Life and He was without sin. (Jn 6:48; 2 Cor 5:21). Therefore the bread of the Eucharist is unleavened.
God also states that one who is uncircumcised, and therefore outside of the covenant, is not allowed to take part in the Passover meal. In the New Covenant, baptism has replaced circumcision (Col 2:11,12) and so the Church does not allow those have not been baptized to receive the Eucharist for the same reason.
The Passover was a testimony throughout the ages of God delivering His people from slavery in Egypt. The Eucharist is also a testimony throughout the ages of God delivering us from the bondage of our sin. Those who stayed behind the blood soaked door were spared death just as we who hide behind the wounds of Jesus will not taste eternal death. God commanded that the Passover be kept forever and we are fulfilling that command when we celebrate the Mass, which we will do until the return of Christ. “Alleluia, Christ our Passover is sacrificed fore us. Therefore let us keep the feast. Alleluia.” (BCP p. 364).