Our baptism makes us to be members of God's Church on earth, and we become children of God; confirmation strengthens us in being faithful to the baptismal promises, and that is to be active for Jesus; Eucharist incorporates us with the life of Christ, his death and his resurrection. The three Sacraments is the completion of what is called: the sacraments of Initiation- Baptism, Confirmation and Eucharist.
A donor who donates blood needs to meet a certain requisite criteria. The purpose is to get suitable and healthy blood for a future blood transfusion. When blood is administered to a person, it not only enters the bloodstream of that person, but it becomes part of that person, and spreads throughout the whole body. Receiving the Blood of Christ at the Eucharist is not a blood transfusion, but rather it is food to nourish our soul. It is the sublime gift Jesus gives us; it allows us to enter into union and participation with the life of the Trinity: Father, Son and Spirit. We hope to become what we have received. By receiving the Body and Blood of Jesus at the Eucharist, we become like Christ and are united to the Trinity. Our spiritual life is fed by his Body and Blood, and we become part of his Body and He becomes part of ours. This holy union is possible because Jesus desires us to take part. It is the foretaste of the heavenly union, which we hope to be united to the lives of the Trinity. No blood, no life, we are related to Jesus by his Blood. This Holy Blood relationship makes us holy.
The Body and Blood of Christ does not remove sin and kill vice, but rather it strengthens our inner life to fight against vices and to resist temptation to sin. To that end, before receiving the Most Holy Body and Blood of Christ, the Church requires a communicant to be free from sin by self- examining one's minds and hearts. It is the preparation of one's inner life to amend any wrong doing, and to reconcile to God before receiving the Eucharist. There is an immediate preparation, and that is fasting for at least an hour before receiving the Holy Communion. The communicant also recognizes that one would never be worthy of receiving the Most Holy Glorious Body and Blood of Christ, but it is Christ himself who desires to come to us, and we welcome him with an open and thankful heart.
The reality is that our physical body inherited some traits of our ancestors. It is passed on from generation to generation. We are children of God and we receive his Body and Blood into our spiritual lives. We inherit what Jesus has gained for us, and that is heir of God's kingdom. The command to eat his Body and Blood is the command to belong to, to be recipient of the gift of everlasting life. When Jesus told the Jews that,
Anyone who does eat my flesh and drink my blood has eternal life Jn 6,54.
They protested and got upset about his teaching. Jesus didn't back down, but reinstated what he had said. He went on to say,
It is the Spirit that gives life, the flesh has nothing to offer. The words I have spoken to you are spirit and they are life' Jn 6,63.
After the consecration, the ordinary bread and wine changed to be truly Body and Blood of Jesus. It is the work of the Spirit. The appearance of the bread and wine remains the same, unchanged; what changes is unseen to our naked eyes.
This is my Body.... this is my Blood Mt 26,26f.
We believe because we have faith in Jesus. We believe his words. We believe in the power of the Spirit, whose supreme power could do amazing things which are beyond human rectification and beyond human comprehension. Our faith's foundation is Jesus himself, His words, His teaching and the power of the Spirit.