John 12:38, "Lord, who has believed our report? To whom has the arm of the Lord been revealed?" - the exact question John quotes to explain the crowd's unbelief.
Who has believed our message? To whom has the arm of Yahweh been revealed?
that the word of Isaiah the prophet might be fulfilled, which he spoke, “Lord, who has believed our report? To whom has the arm of the Lord been revealed?”
The opening question - "who has believed our message?" - names this whole account's own unbelievable quality before a single detail of the Servant's suffering is even described.