Question: "Why is the real presence of Christ in the Lord's Supper such a controversial issue?"
Answer: The “real presence” of the Lord Jesus Christ in the Lord’s Supper is a doctrine of Roman Catholicism (and some other Christian denominations) that teaches that, instead of being symbolic rites, communion and baptism are opportunities for the real presence of God to appear. In the case of communion, they believe once the priest has blessed the wine and the bread, the wine becomes Jesus’ blood and the bread becomes His flesh. They cannot explain how, but they believe this transformation (called transubstantiation) allows God to spiritually nourish the partaker to better serve Him and to be Christ to the lost world.
This concept is hard even for Roman Catholics to fully explain. They believe that Jesus instituted communion as a way of allowing believers to participate in the ongoing sacrifice of the cross. Once the bread and wine are blessed, Christ’s crucifixion is presented again to those in attendance. The ceremony somehow perpetuates the ever-present crucifixion. Even when the service (or Mass) is completed, the leftover bread is kept and venerated in thanks to God for providing the transformation and the nourishment.
There are two major problems with this line of thought. First, there is no way that a ceremony can recreate Jesus’ crucifixion. Several places in the New Testament claim Jesus’ death was “once for all” (Romans 6:10; Hebrews 7:27, 9:12, 10:10; 1 Peter 3:18). There is no mention that the act of the crucifixion, which occurred within the confines of a linear timeline, is somehow free of that timeline to be as eternal as God Himself. The results of that act are certainly timeless, as it was that act that allowed even those before Jesus’ time to be saved. But we have no way of participating in an act that occurred nearly two thousand years ago, except in the symbolic sense.
That is the great controversy of the belief of the real presence of Christ in the Lord’s Supper. But on a practical level, the bread does not become flesh. The wine does not become blood. And no amount of belief is going to make it so. The more urgent issue is the false belief that God’s blessing and nourishment come through that bread and wine. Roman Catholicism teaches that liturgy (taken from the Greek for “work”) is the conduit through which God provides blessing and salvation. Essentially, in addition to placing the priest between the congregants and God, they also place the bread and wine between themselves and God. They believe they are blessed because of their obedience in taking communion, and that blessing literally streams from God through the bread and wine and into their souls.
This is not what Jesus taught. He said, “I am the bread of life” and “It is the Spirit who gives life, the flesh profits nothing; the words that I have spoken to you are spirit and are life” (John 6:48, 63). Jesus is the bread of life, but He is also the Word (John 1:1). The bread that nourishes is the Word of God (Matthew 4:4), not a wafer somehow transformed into the flesh of Jesus. The idea that we have to go through a human ceremony to receive that spiritual nourishment is the type of belief Jesus came to abolish. His death tore the veil in the temple, giving us the ability to have a direct relationship with God (Hebrews 4:16). That veil was not replaced by the act of blessing and eating bread and wine.