Christ speaks often in this way, for example, in John 4, speaking literally of water that He would give:
Joh 4:13 Jesus answered and said unto her, Whosoever drinketh of this water shall thirst again: Joh 4:14 But whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life. Joh 4:15 The woman saith unto him, Sir, give me this water, that I thirst not, neither come hither to draw.
And the case that Christ here speaks literally is even stronger, since Christ does not correct her when she took Him literally, even though we, who have followed His teachings throughout the Gospel of John, would understand it as faith.
Thus Christ's language in John 6 is not obscure or weird, and its direct message is even clearer, insomuch that He bothered to explain Himself twice. First, in the command to believe in response to the "how" of eating, and, secondly, in the reminder that the flesh profits nothing, and it is the spirit which profits, thus pointing us again to a spiritual understanding of His words and a spiritual eating accomplished through faith, exactly as Augustine understood it.
Well, one cannot remember without believing, so all these roads lead to salvation.
But the object of faith is in Christ alone, not in the Eucharist, as otherwise you transform Christ's message here from a call to remember His sacrifice on the cross, to a call to be saved by partaking in a ritual, as if this was the central focus and goal of His death and resurrection. Thus the Thief on the cross is damned because, unlike the Apostles, He did not know that the Gospel was all about the Eucharist, and not the Eucharist for the Gospel.
And St. Paul writes that the Eucharist can condemn (1 Cor. 11:29-30), so presumably it can save also, and of course Jesus in John 6 is very emphatic that the Eucharist saves.
The Sacraments are for our spiritual edification, and those who receive them unworthily bring spiritual condemnation upon themselves and the wrath of God. But the source of the condemnation is not in the elements themselves, or in the water of baptism, but in the faithlessness and the sin of the individual who is unworthily receiving. Thus, what condemns is their lack of faith, their false confession, and so it follows then, that the faithlessness that condemns them, if turned to faithfulness, gives them eternal life, and then makes them worthy to receive all of God's sacraments, as they belong to a holy and pure church for our edification.
He is speaking literally in John 4, for Baptism is literally in water. Same as in John 6, where the Eucharist is literally His flesh and blood and the soul.
the object of faith is in Christ alone, not in the Eucharist
Correct, but it seems to me you say "Christ alone" to you means something like "Christ apart from that Catholic stuff He teaches by mistake". "Observe all things whatsoever I have commanded you" (Matthew 28:20) means also to observe this:
Amen, amen I say unto you: Except you eat the flesh of the Son of man, and drink his blood, you shall not have life in you. He that eateth my flesh, and drinketh my blood, hath everlasting life: and I will raise him up in the last day. (John 6)
the source of the condemnation is not in the elements themselves, or in the water of baptism, but in the faithlessness and the sin of the individual who is unworthily receiving.
The condemnation results from sin, yes; and it is Jesus Who condemns, yes again. But the sin in focus is believing that Protestant stuff that denies the Eucharist, rather than what Christ says and the Holy Scripture records. Paul specifically explains what the sin is: "not discerning the body of the Lord" (1 Cor. 11:29).