The CRUX of the question

I am re-reading the amazing book called The Life of Christ by the priest-archaeologist Giuseppe Ricciotti, and was struck by this sequence:

... was the rite [of the Eucharist] of Jewish or of foreign origin? The critics rummaged through late Judaism but with no satisfactory results. They used the comparative religion method and turned first to totemism and theophagy; then they more carefully studied the rites of Isis and Osiris, and the blood ritual in the cults of Sabatius and Dionysius, while the Eleusinian mysteries and the banquets of Mithra were investigated with still greater attention. Certainly a great deal of rare information was uncovered and many important observations made concerning pagan rites; but when it came to the real crux of the question, namely, their relationship to the Eucharistic rite of early Christianity, the critics mistook fireflies for lanterns and were ready to declare a mosquito the same as an eagle because both have wings and fly and feed on blood.
[Ricciotti, The Life of Christ § 547 p. 578, emphasis added]

If I had the time I might give you some interesting coordinations between this and GKC's writing - or in the good priest's wonderful "verbal fireworks" of analogy... (not to mention speculating as to whether he ever read any GKC) but it is far more appropriate for me to quote the companion text from GKC's work on our Lord - a fragment which comes in the earlier half of the book, and is perhaps the most stunning and deep - dare I say Johannine? - texts of all his writing. I admit I have broken it in the middle, but you will hear the remainder in three days... Enough; read and contemplate, and be silent:

One incident occurred once or twice again and began to arouse irritation out of proportion to its insignificance. It was not exactly what these provincials said; though of course it sounded queer enough. They seemed to be saying that God was dead and that they themselves had seen him die. This might be one of the many manias produced by the despair of the age; only they did not seem particularly despairing. They seemed quite unnaturally joyful about it, and gave the reason that the death of God had allowed them to eat him and drink his blood.
[GKC The Everlasting Man CW2:295-6]