This is the final section of Jesus’ teaching after the multiplication of loaves and fishes. His words have been difficult to understand, and his hearers have been reacting to them. The decisive moment has come. Jesus’ talk of their eating his body is too much for some because they take it literally. For them, Jesus is making an impossible demand on them and so they decide to follow him no more.
The twelve, who also find his words difficult to understand, continue to trust in him and to follow him. Nobody hears the message of the kingdom as preached by Jesus can remain indifferent to it.