I’ll take the words of Jesus Christ:
“Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you” (Jn 6:53).
And where do you find that Holy Communion? In the Catholic Church!
There is no Holy Communion in Scripture. There is the Lord's Supper. It is celebrated until He returns, among believers everywhere.
I would encourage you to re-read John chapter 6 with a mind and heart open to the Holy Spirit and not anyone's doctrine. "Throughout" the chapter, the "main thing" that Jesus challenges His disciples on is "belief in Him" - communion is the respective metaphor. Jesus uses metaphors throughout His teachings. Jesus also told Nicodemus that he needed to be born-again. Like the disciples in John 6, Nicodemus responded with his natural mind, "How can a man be born when he is old."
Read further in John 6: 61-64, where Jesus speaks to the disciples murmurming about your view of communion.
"When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you? What and if ye shall see the Son of man ascend up where he was before? It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life. But there are some of you that believe not."
Did you get that? "It is the spirit that gives life; the flesh profit nothing: the Words that I speak unto you, they are Spirit, and they are Life."
To be clear, are you saying that Catholic communion is necessary for salvation?
Matthew 26:29 I tell you I will not drink again of this fruit of the vine until that day when I drink it new with you in my Father’s kingdom.”
Mark 14:25 Truly, I say to you, I will not drink again of the fruit of the vine until that day when I drink it new in the kingdom of God.”
Luke 22:18 For I tell you that from now on I will not drink of the fruit of the vine until the kingdom of God comes.”
John 6:63 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 3:3-8 Jesus answered him,“Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.” Nicodemus said to him, “How can a man be born when he is old? Can he enter a second time into his mother's womb and be born?” Jesus answered, “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. Do not marvel that I said to you, ‘You must be born again.’ The wind blows where it wishes, and you hear its sound, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit.”
John 3:14-18 And as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, that whoever believes in him may have eternal life. “For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God.
John 5:24 Truly, truly, I say to you, whoever hears my word and believes him who sent me has eternal life. He does not come into judgment, but has passed from death to life.
John 6:40 For this is the will of my Father, that everyone who looks on the Son and believes in him should have eternal life, and I will raise him up on the last day.”
John 11:25-26 Jesus said to her, “I am the resurrection and the life. Whoever believes in me, though he die, yet shall he live, and everyone who lives and believes in me shall never die. Do you believe this?”
So therefore you exclude all those who reject the Cath (erroneous , metaphysical) l understanding of the Lord's supper from having eternal life. Meaning you reject Lumen Gentium on that, and expose yourself as a schismatic TradCath. At least you made that damnably clear.