Jesus instituted the taking of bread and wine as a ritual for Christians at the Passover supper he ate with his disciples prior to his betrayal and capture (Matt 26:26-29, Mark 14:22-25, Luke 22:14-20, 1 Cor 11:23-26). He compares the bread to his body and the wine to his blood. These are to be symbols by which Christians are to regularly remember Jesus (Luke 22:19; 1 Cor 11:24-25). As Paul summarises:
For as often as you eat this bread and drink the cup, you proclaim the Lord’s death until he comes (1 Cor 11:26)
Neither the gospels nor Paul describe taking the bread and wine as essential for salvation. Paul does emphasize the significance of the bread and wine, saying that when the church meets to take bread and wine they should do so orderly (1 Cor 11:33-34), in harmony (v18), and not for feasting or getting drunk (v21-22). Pauls says
Whoever, therefore, 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. Let a person examine himself, then, and so eat of the bread and drink of the cup. For anyone who eats and drinks without discerning the body eats and drinks judgment on himself (1 Cor 11:27-29)
Clearly Paul considered the bread and wine to be sacred symbols that should not be disrespected or defiled. But he does not say that taking them is essential for salvation.
We should not expect the taking of the bread and wine to be essential for salvation because we are told that are salvation comes from the grace of God, not from our own works:
For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast. For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them.
We are not saved by ritual acts but by the acceptance of God’s grace through faith in Jesus Christ. Symbolic acts, like baptism, are ways that we demonstrate our faith and committment. Taking bread and wine is another symbolic act by which those who have committed themselves to Christ demonstrate their ongoing faith and acceptance of God’s grace.
There is one passage which might seem to indicate that taking bread and wine is essential for salvation. This is where Jesus says:
Truly, truly, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Whoever feeds on my flesh and drinks my blood has eternal life, and I will raise him up on the last day. (John 6:53-54)
Taken out of context this might appear to say that unless you take the bread and wine then you will not be resurrected. However in context, it is clear that Jesus is not talking about the physical act of eating and drinking. He says:
It is the Spirit who gives life; the flesh is no help at all. The words that I have spoken to you are spirit and life (John 6:63)
Jesus is the bread of life because he, like bread, gives life. Normal bread only gives temporary life, but Jesus gives eternal life (John 6:48-50). Jesus was to give his flesh (i.e. the bread) for the life of the world (v51). To be saved, what is required is for people to receive Jesus, which he describes as feeding on his flesh (v54). Whoever receives Jesus, enters into a relationship with him (v56). Jesus says that in the same way that he lives because of his relationship with his Father so believers can live through their relationship with Jesus (v57). And believers enter into this relationship through faith (v40). So what Jesus is describing is how believers receive eternal life through their relationship with Jesus, not through some physical act.
Jesus answered them, “This is the work of God, that you believe in him whom he has sent.” (John 6:29)