Many churches today hold communion to be one of the most holy rites in Christianity, in which the faithful can grow closer to God and the community of the church. Yet, the whole sequence at the Last Supper, in which Jesus tells his disciples to eat bread and drink wine while mentioning that they're metaphorically (or kind of not, as many transubstantiation-believing Catholics have it) consuming his own body and blood, can be creepy.
That's not just a modern sense of ickiness, either. Some of Jesus' own followers were so unnerved by his communion statements that they abandoned ship. In John 6:53-66, after Jesus makes his claim of communion — saying, "so he that eateth me, even he shall live by me" — some disciples tell him, "This is an hard saying; who can hear it?" Jesus doubles down on his statement, and so some followers "walked no more with him."
This surely has something to do with Jewish dietary laws, which today forbid cannibalism except to save lives in the most dire circumstances. That's part of a broader concept known as pikuach nefesh, in which someone must do everything they reasonably can to save a life. Leviticus 19:16 is often cited as support for pikuach nefesh, saying, "Neither shalt thou stand against the blood of thy neighbor." However, it's not as if those at the Last Supper were starving to death, meaning that Jesus' words were likely supremely controversial and unnerving.
