Doesn't John 6, 'eat my flesh, drink my blood,' prove the real presence?

You are reaching for a text that sounds like it settles the matter, and it is fair to reach for it. 'Eat my flesh, drink my blood' is vivid, bodily language, and if you take it at face value it does seem to point straight at a real, physical presence. Anyone would hear it that way at first.

And you are right that the chapter is not throwaway. It is one of the deepest things Yeshua (Jesus) ever said about Himself, life depending on total dependence on Him. It should not be flattened into a mere figure of speech and dropped.

You may also, if you read it slowly, feel a snag: the word that governs the whole discourse is not eating, it is believing. That snag is the thread to pull.

Here is the move to set down: lifting John 6 out of its own year and laying the later supper over it. The chapter equates eating with believing from the start. 'This is the work of God, that you believe' (John 6:29). 'Whoever comes to Me shall not hunger, and whoever believes in Me shall never thirst' (John 6:35). 'Whoever believes has eternal life' (John 6:47). And when the hard talk of eating His flesh scandalized the room, Yeshua Himself turned toward the carnal hearing, not into it: 'It is the Spirit who gives life; the flesh profits nothing' (John 6:63). A defender of the literal reading will say 'the flesh' there means unaided human understanding, and that verse alone will not end the argument by itself; but read in the flow of a chapter that has equated eating with believing from the first verse, the natural force of the line is a warning against hearing 'eat My flesh' as literal ingestion.

Two more things the literal reading has to answer for. 'Eat my flesh, drink my blood' is Hebraic idiom for total internalizing, the way bread becomes the body that eats it, and a wooden reading would have the Torah-keeping Yeshua commanding Torah-observant Jews to drink blood, which the Torah forbids flatly (Leviticus 17:10-14). And the chronology: John 6 sits about a year before the Last Supper (John 6:4), with no cup, no bread broken, no 'do this.' What offended the crowd was the Person and His claim, not a wafer's metaphysics (John 6:60-66).

Do not take it from me. Read John 6 in one sitting and count how many times the point is believing. Then ask whether the chapter founds a rite, or whether the rite was carried back into it.