When Jesus drove out demons some attributed it to his being aligned with the prince of demons rather than Jesus being the kingdom of God among them. Others also acted in unbelief by demanding further signs. Jesus calls such people “an evil generation” no less offensive than the uncleanness caused by those under the influence of demons.
In response to their request for a sign Jesus offers only the sign of Jonah. In Luke’s gospel, the sign of Jonah refers to his preaching a message of judgment which is all his contemporaries can expect. Jesus highlights the responses of the Queen of Sheba and the people of Nineveh in the Old Testament. Sheba and Nineveh are geographically located in the extreme south and north. The point is that Gentiles who believe God’s word will condemn this evil unbelieving generation. Jonah and Solomon represent prophetic speaking and wisdom – Jesus is greater than both representatives and therefore so are his words. Rejection of his words will therefore bring an even greater judgment.
Jesus concludes this periscope by comparing himself to a lamp – not hidden but on a stand. He is the light of God’s word and wisdom – and therefore his open display requires no signs.