The place of worship - our nave - our sanctuary - our altar - is not just symbolic of God's presence. By the promise of Jesus the place where we gather together in His Name is the place where He comes into our midst to serve us (Matthew 18:20). Where He is, the Father and the Holy Spirit are present as well! His presence calls for our reverence and our respect as Moses experienced in the wilderness - "Then he said, "Do not come near; take your sandals off your feet, for the place on which you are standing is holy ground" (Exodus 3:5).
How do we take off our shoes to mark the holy ground of God's presence in the Divine Service? By invoking the presence of the Holy Trinity and speaking our "Amen" to His presence. By confessing our sin and receiving His holy Absolution. By giving reverent attention to His holy Word. By receiving in faith the holy body of Christ to eat and His holy blood to drink.
When it comes to the moment of the beginning and the end of the real presence, we don't pretend to determine that with watch in hand. The Lutheran view is that the consecrated bread is the body of Christ also when it lies on the altar or when the pastor holds it in his hand. It is not Scriptural to limit the real presence to the moment when the elements are orally received.
That is why the elements are treated as unique and holy not only until the last person has communed, but until the elements have been consumed. Since they were set apart by the words of the Risen Christ who has come into our midst to teach us and to feed us, they are used as He intends. The pastor and those assisting will take just a brief moment after the last person has communed to consume any that remains of the body and the blood that Jesus has set apart by His words of institution during that Divine Service. For the same reason the altar guild members treat with reverence the vessels in which the blood has been served to us. Not only the chalice, but also the individual glasses are rinsed with clear water and that water is placed on the ground. Then the vessels are cleaned more thoroughly for the next use.
God bless us all with reverent and joyful sense of the gifts that our heavenly Bridegroom comes to serve us His Bride. Amid all the passing treasures of this brief life - the treasures He bestows well up to eternal life (John 6).
Draw near and take the body of the Lord, And drink the holy blood for you out-poured;
Offered was He for greatest and for least, Himself the victim and hiimself the priest.