The most challenging sermon that Jesus ever preached was not the Sermon on the Mount; it was the discourse he gave in the Capernaum synagogue after the miracle of multiplying the loaves and fish. The Sermon on the Mount—with its calls for love of one’s enemy, the cleansing of the interior self, and nonresistance to evil—was certainly intellectually confounding. But the talk that Jesus gave at Capernaum concerning the sacrament of his Body and Blood was not only philosophically problematic; it was, quite literally, revolting. Even at a distance of two thousand years and after volumes of theological reflection, readers today can still find his words awfully hard to accept. We can tolerate easily enough the claim that Jesus is a spiritual teacher of great importance; we might even accept that his person is central in regard to our relation to God. But that his flesh is real food and his blood real drink? That the ingesting of these elements is essential to gaining eternal life? Even the most sympathetic of contemporary listeners is likely to react the same way many in Jesus’ original audience reacted: with a shake of the head and perhaps even a shudder of disgust.

To understand why Jesus’ own hearers would have responded in a particularly negative way to these words, we must remember the clear and repeated prohibitions in the Hebrew Scriptures against the consuming of flesh with blood. In Genesis 9:3–4, we find this: “Every moving thing that lives shall be food for you; and just as I gave you the green plants, I give you everything. Only, you shall not eat flesh with its life, that is, its blood.” In Leviticus 3:17, we read, “It shall be a perpetual statute throughout your generations, in all your settlements: you must not eat any fat or any blood.” And in Deuteronomy 12:23, we discover, “Only be sure that you do not eat the blood; for the blood is the life, and you shall not eat the life with the meat.” Finally, the expression “to eat someone’s flesh” was commonly used in Jesus’ time to designate the most vicious and unwarranted kind of attack. Therefore, when Jesus says, “I am the living bread that came down from heaven. . . . The bread that I will give for the life of the world is my flesh,” he is implying something about as nauseating and religiously objectionable as possible. It is, accordingly, a rather remarkable understatement when John writes, “The Jews then disputed among themselves, saying, ‘How can this man give us his flesh to eat?’”
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​So what does Jesus do when confronted with this objection? One would think that, in order to mollify his opponents, he would take the opportunity to soften his rhetoric, to offer a metaphorical or symbolic interpretation of his words, so as at least to answer the most obvious difficulties. Instead, he intensifies what he had said: “Very truly, I tell you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you.” The Greek term behind “eat” here is not the usual phagein but rather trogein, a word customarily used to describe the way animals devour their food. We might render it “gnaw” or “chomp.” Therefore, to those who are revolted by the realism of his language, Jesus says, essentially, “Unless you gnaw on my flesh . . . you have no life in you.”