Claim. When directly asked “Are you Elijah?” John the Baptist answered “I am not” (21), contradicting Jesus’s explicit testimony that “Elijah has already come… he is John the Baptist” (Matt 17:12-13) — and his denial blocked the Jewish people from accepting Jesus’s messianic claim.
Elaboration. Per 2.1. The Jewish Belief in the Return of Elijah: God had directly revealed to JtB that Jesus was the Messiah; JtB bore witness to this revelation (“I have seen and have borne witness that this is the Son of God,” 34). DP’s reasoning: “Therefore, John should have realized through his own wisdom that he was the returning Elijah. Even if John did not realize this fact, since God had revealed to him that Jesus was the Messiah, he should have accepted the testimony of Jesus and, in obedience, proclaimed himself to be Elijah.”
Instead, JtB’s flat denial gave the Jewish leadership the textual hook they needed to dismiss Jesus’s whole messianic claim: if Elijah had not come (per JtB), then the Messiah could not have come either (per Malachi). Jesus’s hedged statement “if you are willing to accept it, he is Elijah who is to come” (Matt 11:14) signals that he expected this skeptical response.
DP frames this as ignorance with major providential cost, not malice — JtB simply did not understand the structural role he had inherited from Elijah’s incomplete mission. But the cost was the collapse of the credibility-comparison (JtB vs Jesus).
See also. dp-jtb-faithlessness-was-main-reason-jesus-had-to-die, dp-jtb-was-elijah-by-mission-not-soul-transmigration