While still more people gathered in the crowd, he said to them, "This generation is an evil generation; it seeks a sign, but no sign will be given it, except the sign of Jonah. Just as Jonah became a sign to the Ninevites, so will the Son of Man be to this generation. At the judgment the queen of the south will rise with the men of this generation and she will condemn them, because she came from the ends of the earth to hear the wisdom of Solomon, and there is something greater than Solomon here. At the judgment the men of Nineveh will arise with this generation and condemn it, because at the preaching of Jonah they repented, and there is something greater than Jonah here. (Lk 11:29-32)
People long for a sign. In a materialistic society people ask for guarantee. Before buying a thing or a product people want to know whether the material will last ofr a time or whether that thing is worth the cost etc. In a religious context a sign is asked for. This is to know the significance of the person or the action or its meaning an relevance.
Son of man will be like Jonah to this generation. What was Jonah like, to the Ninivites? Jonah was a run-away prophet. He was a cast-away prophet. He was a swallowed up prophet. He was a grumbling prophet and so on. With all these he was always falling back to God. Whatever might have been the negative situation bu the prophet was a man of God (he fell back to God and gave primacy to God in his own way)
Jesus is like the prophet in the sense of giving centrality to God and primacy to God. The Ninivites realized that they could not go away from God. They have to return to God by all means. There is only way and that is conversion to God. Jesus also peaches the same lesson to the people. In this sens of preaching he like prophet Jonah. He is a sign like Jonah.
