It is based on scripture. I’m glad you brought John 6 to light. John did say this was a hard thing for them to hear. But only because they didn’t understand Jesus’ symbolic language. Dr. this doesn’t make any sense at all. That Jesus would confuse the crowds with symbolic language and not help them understand what he was actually saying. And then say that you MUST eat his symbolic body and eat his symbolic blood to have everlasting life. Quite the opposite. The crowds left because they took him literally, and he was speaking literally. Jesus taught the apostles. The apostles taught their descendants. The descendants of the apostles taught their descendants. At this point there still was not a bible and all the Catholic Church’s everywhere, taught the Real Presence of Christ in the Eucharist. No where was The Church teaching a symbolic Last Supper. No where. I highlighted St Ignatius and Justin Martyr earlier. Here’s Clement of Alexandria.
“For the blood of the grape–that is, the Word–desired to be mixed with water, as His blood is mingled with salvation. And the blood of the Lord is twofold. For there is the blood of His flesh, by which we are redeemed from corruption; and the spiritual, that by which we are anointed. And to drink the blood of Jesus, is to become partaker of the Lord’s immortality; the Spirit being the energetic principle of the Word, as blood is of flesh. Accordingly, as wine is blended with water, so is the Spirit with man. And the one, the mixture of wine and water, nourishes to faith; while the other, the Spirit, conducts to immortality. And the mixture of both–of the water and of the Word–is called Eucharist, renowned and glorious grace; and they who by faith partake of it are sanctified both in body and soul.” Clement of Alexandria, The Instructor, 2 (ante A.D. 202).
Jesus let those disciples leave because 1. He knew from the beginnig they were not with him and