"Jonah was a 'sign' to the Ninevites in that he appeared as one delivered from death. It was the knowledge of this which attested his preaching and caused their repentance. The point of the comparison with Jonah lies, therefore, in 'the authorization of the divine messenger by deliverance from death'. Jesus' preaching, which his hearers are rejecting, will in due course be attested by a still greater deliverance; therefore their condemnation will be the greater (verse 41).
The theological correspondence, the repeated principle of God's working, lies in the sending of a preacher of repentance, whose mission is attested by a miraculous act of deliverance. As God sent Jonah to the Ninevites, so Jesus is sent to the Jews of his day. The typology thus places Jesus in the succession of God's prophetic messengers to men. Now. in the sending of a 'greater then Jonah' (verse 41), this long-continued method of God's working has reached its climax, and in a greater act of deliverance God will accredit this supreme call to repentance. Neneveh had repented at the preaching of Jonah; Jesus' hearers are thus challenged to do likewise. But the antitype is greater than the type; failure to repent will, therefore, incur a greater condemnation than that which Nineveh's repentance averted."
- R. T. France