And when the people were gathered thick together, he began to say, This is an evil generation: they seek a sign; and there shall no sign be given it, but the sign of Jonas the prophet. For as Jonas was a sign unto the Ninevites, so shall also the Son of man be to this generation. Luke 11:29-30

Throughout the history of creation , people are looking for a sign. When Jesus was on Earth, the Jews were demanding a sign from Christ, even though Jesus was the sign. He is the Bread that came down from Heaven, the Manna from God (John 6) However either the people didn’t understand the fulfillment of Jesus or they didn’t want to 

So Jesus told them the sign of Jonah was already given to you. Now his Jewish audience would be familiar with the prophet Jonah and his story. However again, they didn’t understand what Jesus was revealing to them, and I think most Christians even today don’t understand the relevance of Jonah with the coming of Christ

A couple quick points to make so you understand how Jonah was a foreshadow of Christ. First, the mission of Jonah was to preach to the Ninevites, who were Gentiles. This is a foreshadow of the New Covenant , and also a reason why Jonah didn’t want to preach to Gentiles. Secondly, the Ninevites came to salvation through repentance and faith in God. God spared the Ninevites based on them repenting and putting their faith in Him, the same that we are saved through Christ. Lastly, when Jonah was swallowed in the whales and spit out after 3 days, was a foreshadow of Christ’s resurrection in the tomb. (Matthew 12:40) 

The queen of the south shall rise up in the judgment with the men of this generation, and condemn them: for she came from the utmost parts of the earth to hear the wisdom of Solomon; and, behold, a greater than Solomon is here. The men of Nineve shall rise up in the judgment with this generation, and shall condemn it: for they repented at the preaching of Jonas; and, behold, a greater than Jonas is here. Luke 11:31-32

Jesus is revealing here, that the Old Testament and all of its prophets and patriarchs, are a foreshadow of himself. As we know King Solomon was the wisest man to live (1 Kings 4:30) However Jesus says “ A greater Solomon is here” , revealing Jesus is the wisest man to ever live, of course because He is the Son of God. However Solomon’s wisdom and teachings were just a foreshadow of the Messiah to come

Next Jesus says “A greater Jonah is here” ,  meaning Jesus is going to preach to the entire world about repentance and salvation. Not only that Jesus spent 3 days in the grave, not a whale and rose from the dead forever, defeating sin and death. Jonah was just another foreshadow of the Messiah to come

However that generation is this generation today still demand a sign. Even though Christ rose from the dead, we still demand proof of Gods existence, oh this wicked and perverse generation, Jesus is the sign, repent or perish! Amen!