Catholic dogma is that during the Consecration at Mass the bread and wine become the the Real Presence of Jesus – His Body and Blood. So, after someone has received Communion, how long does the Flesh and Blood of Jesus remain as such? It is something I had never thought of. Till I read this.
How long does the change in substance last?
Because the change in substance is a change in the thing itself, it lasts until it is no more. For us, the substantial change in the bread and wine remains until these are changed into our substance as happens to all food through digestion. This also helps to explain the reverence for the bread that extends beyond the actual Mass.
What happens to us when we receive Holy Communion?
Just as we nourish our bodies by eating, so we nourish our spiritual lives by contact with God’s presence in the eucharistic bread and wine. Through Holy Communion, we become what we eat — the Body of Christ. St. Cyril of Alexandria understood that “When we ingest the Eucharist, in reality we are ingesting the Godhead … Because his Body and Blood are diffused through our members, we become partakers of the divine nature.” The divine reality works from within us — this is what grace is all about — God’s divine life present in us is at work transforming us from within. As digestion transforms the bread and wine into ourselves, so too are we being transformed on the spiritual level into the divine through contact with God’s holy reality.
Jesus did say to His disciples: “19 Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.” Matthew 28:19-20 (NIV)
I believe Jesus is always with us – because He said He is.