At the Last Supper Christ instituted the Eucharist as Catholics understand it

This is a topic I find interesting and I look forward to hearing his arguments. Though it sounds like my opponent is well acquainted with this topic, I will give a little background into what is being debated especially for the benefit of the audience. Catholics believe that at the Last Supper Christ instituted the sacrament of the Eucharist. In this sacrament, Christ turned the bread and wine in His hands into His actual body and blood. The appearance of the bread and wine did not change, but their essence did. This is called transubstantiation, which means that the very essence of something, the bread and wine, is taken away and replaced with something else, Christ himself. It still looked like bread and wine, but since God is all powerful he was able to take the place of the bread and wine without even changing their appearances. Most Protestant Christians on the other hand believe that what Christ did was merely give men a symbol of His body and blood and sacrifice on the cross (please correct me SkepticsAskHere if you believe something different). Since both sides agree on the legitimacy of the bible as God's word, both of us being Christians, I hope that we can both use strong Biblical arguments to support our points. I hope that both sides will strive to prove that it is either more likely Christ really did initiate transubstantiation or that he did not. Now to present my arguments: Contention 1: The Last Supper Luke 22:19-20 And he took bread, gave thanks and broke it, and gave it to them, saying, "This is my body given for you; do this in remembrance of me. " 20 In the same way, after the supper he took the cup, saying, "This cup is the new covenant in my blood, which is poured out for you. . http://www.biblegateway.com... Matthew 26:26-28 While they were eating, Jesus took bread, and when he had given thanks, he broke it and gave it to his disciples, saying, "Take and eat; this is my body. " 27 Then he took a cup, and when he had given thanks, he gave it to them, saying, "Drink from it, all of you. 28 This is my blood of the[b] covenant, which is poured out for many for the forgiveness of sins. . http://www.biblegateway.com... In these accounts of the Last Supper, we see that Christ said that "this is my body" concerning the bread, and "this is my blood" concerning the wine. Neither before nor after does Christ say that He is merely talking symbolically. If Christ doesn't tell us that He is speaking symbolically or give us any context to cause us to believe otherwise, then we must take Him at His word and believe that the bread really is His body and the wine really is His blood. Contention 2: John 6 John 6:53-59 53 Jesus said to them, "Very truly I tell you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. 54 Whoever eats my flesh and drinks my blood has eternal life, and I will raise them up at the last day. 55 For my flesh is real food and my blood is real drink. 56 Whoever eats my flesh and drinks my blood remains in me, and I in them. 57 Just as the living Father sent me and I live because of the Father, so the one who feeds on me will live because of me. 58 This is the bread that came down from heaven. Your ancestors ate manna and died, but whoever feeds on this bread will live forever. " 59 He said this while teaching in the synagogue in Capernaum. . http://www.biblegateway.com... In this passage, Christ says several times that the people must eat His body and drink His blood. Since nowhere else in the bible does Christ condone cannibalism, He is obviously foreshadowing what He would do at the Last Supper. By turning bread and wine into His body and blood, He would indeed make it possible for these people to consume His body and blood. Contention 3: 1 Corinthians 11 1 Corinthians 11:27-29 27(AB) Whoever, therefore, eats the bread or drinks the cup of the Lord(AC) in an unworthy manner will be guilty concerning(AD) the body and blood of the Lord. 28(AE) Let a person examine himself, then, and so eat of the bread and drink of the cup. 29For anyone who eats and drinks without discerning the body eats and drinks judgment on himself. . http://www.biblegateway.com... In this passage, St. Paul tells us that whoever "eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty concerning the body and blood of the Lord. " To take the words at their face value would mean that Paul is condemning those in Corinth who were receiving the Eucharist (for Christ passed on the power to change bread and wine into his body and blood) in an unworthy manner and reminding them that they are desecrating the very body and blood of Christ himself. There is no suggestion from Paul that he is speaking symbolically, so must indeed take this statement at face value, showing that Christ did indeed institute the Eucharist. I hope that my points have been clear and understandable, and I look forward to hearing my opponent's arguments.