Matthew 12:38 says, Then certain of the scribes and of the Pharisees answered, saying, Master, we would see a sign from thee.  The scribes and Pharisees were always quick to attempt to discredit Jesus.  They asked Jesus to show them some sign that He was indeed the Messiah.  I believe they asked more from the belief that Jesus could not give them a sign than the hope that He would.  Some people today attempt to put conditions on their believing God.  They demand some particular sign before they will even acknowledge that God exists.  Verse thirty-nine states, But he answered and said unto them, An evil and adulterous generation seeketh after a sign; and there shall no sign be given to it, but the sign of the prophet Jonas:  Jesus told them, and tells us as well, that those who seek a sign before believing in Jesus as Savior are a wicked and adulterous generation.  Jesus further said that the only sign would be the sign of Jonah.  Verse forty continues, For as Jonas was three days and three nights in the whale’s belly; so shall the Son of man be three days and three nights in the heart of the earth.  Jesus said that just as Jonah spent three days and nights in the belly of the whale, so would Jesus, the Messiah, spend three days and nights in the grave.  Then, just as Jonah was rescued from the whale, so would Jesus be resurrected from the grave.  For those Jesus was speaking to the sign was yet to come, but for us today it is something we look back on through faith as an accomplished fact.  Verse forty-one declares, The men of Nineveh shall rise in judgment with this generation, and shall condemn it: because they repented at the preaching of Jonas; and, behold, a greater than Jonas is here.  Even though God had been ready to destroy Ninevah before Jonah preached God's word to them, they repented.  Jesus said that the people of Nineveh could rise in judgment against God's chosen people around Jesus who did not repent at the preaching of Jesus, Who was much greater than Jonah.  Verse forty-two says, The queen of the south shall rise up in the judgment with this generation, and shall condemn it: for she came from the uttermost parts of the earth to hear the wisdom of Solomon; and, behold, a greater than Solomon is here.  Jesus said that the queen of the south came to hear the wisdom of Solomon, but that those around Jesus refused to hear Him, though He was much greater than Solomon.  There will always be people who will listen to the wisdom of the world more quickly than they will to the gospel of Christ.  Verse forty-three says, When the unclean spirit is gone out of a man, he walketh through dry places, seeking rest, and findeth none. Jesus said that even when the unclean spirits leave a person that they may still not have a safe place to stay.  When we accept Jesus as our Savior and Lord, our situation in life does not necessarily change.  The thief on the cross was still on the cross after he accepted Jesus.  Verse forty-four says, Then he saith, I will return into my house from whence I came out; and when he is come, he findeth it empty, swept, and garnished.  The man cleansed of the evil spirit returned to where he had lived and saw it as a better place to be than where he was after he was cleansed of the spirit.  Verse forty-five says, Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first. Even so shall it be also unto this wicked generation.  Upon going in to where he had lived, the man became much worse off than he was before.  I believe this is an analogy to deciding to follow Christ simply for material reasons, and then deciding that things were better before.  We can never follow Jesus simply hoping for a better life materially and find peace and happiness.  Jesus said that just as the man who had the demon cast out but returned to where he had lived and ended up in a worse situation, that it would be the same for that wicked generation.  They had Jesus with them willing to heal them spiritually, but were often following Him for material reasons and soon turned away.  Jesus has already freed everyone from the power of sin, but often people say that it just cost them too much materially to follow Him, so they return to where they had been before spiritually, and they are even worse off than they were before.