How John 20:31 refutes transubstantiation or the need for the sacrament of communion

Despite no mention of bread and wine turning into Jesus, Catholics say that John 6 supports the doctrine.

John 20:31 says that the Gospel of John alone is enough for salvation and belief in Jesus. The verse goes, "Jesus did many other miraculous wonders in the presence of his disciples which are not recorded in this book. But I have written of the other signs so that you may believe that Jesus is the Christ and the Son of God so that by believing you may have life in his name". In other words, it gives enough evidence for one to base belief on and be saved by that belief coupled with repentance. When John is enough and when John appeals to other scripture as scripture it implies that there is no need for anything outside the Bible. Catholics say this interpretation infers that no Bible book is needed but the gospel of John. The Bible might be sufficient for our salvation but that does not mean that it cannot repeat itself and contain material we don't need for salvation. The Bible being sufficient for salvation does not mean that doctrines such as the virgin birth of Jesus need to be known about for salvation though the Bible teaches the virgin birth doctrine. An inspired book that contains all the basics of the gospel of John can be sufficient. But what about the rest of the Bible? It isn't needed yes but that doesn't mean it is not inspired. It doesn't mean the whole Bible isn't the only word of God and sufficient. The Gospel of John author never says that belief means belief that is acted out as well as just believed. He speaks as if he means mere belief. When that is the case, the gospel teaches salvation by belief alone without good works or sacraments as taught by many at the Protestant Reformation. This proves that the only candidate for being an additional source of the word of God, Catholic tradition, is in fact only the word of man and is to be dismissed. The focus on belief shows that the eating and drinking of Jesus mentioned in John 6 means assimilating Jesus by faith. When you believe you enter into a union with Jesus that is so close that you can use the image that you are eating and drinking him.
 
You will see from my page, Faith Only Gospel, that the New Testament teaches that salvation or justification (being considered good in God’s eyes) is gained by faith alone and not by good works and good works are only the fruits of being saved not the cause of salvation or justification. That means that faith unites you with Christ in the closest possible union and not the Eucharist. That means the body and blood of Christ cannot be present in the Eucharist. That is why evangelicals, believers in salvation by faith alone, teach either that communion is just a symbolical ceremony or that we feed on Christ by faith which means that communion is a sign that we renew our faith by which we received Christ in the closest way. The Mass denies the gospel doctrine of salvation by faith alone for you have to do a work and do good works to be fit to receive Christ at Mass. The gospel doctrine is that you have nothing to contribute to your salvation and God does it all.
 
God is spirit and he is goodness and holiness and righteousness and wisdom. It follows then that we can only experience him by his effects. In other words, to worry about eating bodies and gazing up at images to get in the mood for praying is idolatry. John's gospel has Jesus saying to the Samaritan woman that God is spirit and those who worship him must worship him in spirit and truth. Jesus told the Samaritan woman that salvation was from the Jews - in the context of God being spirit and truth means that the Jews who adored a God without any material images or mental images were right to do so.  Also, the differences between Jews and Samaritans in terms of belief was insignificant but if they were enough to mean they knew nothing of God then how much less does a Catholic who worships bread as God know God.  Jesus was clear only the Jews knew God.  He said in John 6 after saying that his body was food and his blood drink that his words were spirit - meaning his intention was to keep the people steered towards the Jewish vision of God. There was no room in his faith for bodies looking like bread or for the worship of idols or the veneration of images.

To get us to link the symbolism in the talk with the woman with John 6 John goes as far as to have Jesus take leave of the woman and then talk of metaphorical food - obviously bread! 

Meanwhile his disciples urged him, “Rabbi, eat something.”

But he said to them, “I have food to eat that you know nothing about.”

Then his disciples said to each other, “Could someone have brought him food?”

“My food,” said Jesus, “is to do the will of him who sent me and to finish his work.

One theme in the story is how material food and water do nothing at all to start you off getting saved or to help you get saved.  “Everyone who drinks this water will be thirsty again, but whoever drinks the water I give them will never thirst. Indeed, the water I give them will become in them a spring of water welling up to eternal life.”  Catholic communion then blocks salvation.  "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.  This is the bread that came down from heaven. Your ancestors ate manna and died, but whoever feeds on this bread will live forever" means that if it is wrongly taken to mean communion bread and wine then the only life you will get will be life forever in Hell!