This Supper is a physical sign of a spiritual reality. Christ came in flesh and blood, to redeem us, body and soul, from our sin. God has given physical signs and promises to His people all along, that were pointing to Christ’s coming, washing, feeding and blessing His people. A rainbow, circumcision, a land, descendants, blood of a lamb, Passover feast, unleavened bread, Sabbath, sacrifices, bread, lamps, altar, basin, ark, tabernacle, temple, prophets laying on their side, packing bags, marrying prostitutes, calling down fire; then baptism, miracles like water to wine, Lord’s Supper. Lots of physical signs. And while the reality it points to is primarily spiritual, it is also a physical one. David was told his descendant, from his very loins, would rule forever. And Jesus does so now, as a body and soul. One day your body will be fully restored.
But this happens because of the spiritual reality at work, the covenant. In shedding His blood at the cross, Jesus kept His covenant to redeem us. He was a faithful Son to His Father. His Father kept His covenant to accept us, and to exalt His Son, and give us to Him. He is a faithful Father to His Son, and to us.