“Then some of the scribes and Pharisees said to Him, Teacher, we desire to see a sign or miracle from You [proving that You are what You claim to be].
But He replied to them, “An evil and adulterous generation (a generation morally unfaithful to God) seeks and demands a sign; but no sign shall be given to it except the sign of the prophet Jonah.
For even as Jonah was three days and three nights in the belly of the sea monster, so will the Son of Man be three days and three nights in the heart of the earth.
The men of Nineveh will stand up at the judgment with this generation and condemn it; for they repented at the preaching of Jonah, and behold, Someone more and greater than Jonah is here!
The queen of the South will stand up at the judgment with this generation and condemn it; for she came from the ends of the earth to listen to the Wisdom of Solomon, and behold, Someone more and greater than Solomon is here.” Matthew 12: 38-42 AMP
Those who do not believe in Jesus call for a miraculous sign (38). The Pharisees and scribes basically demanded a sign from Jesus. What were they looking for in a sign, and why would Jesus not give them one?
They were looking for some amazing event or miracle that would convince them that He was the Messiah. Of course, He had been doing miracles right and left--but they seemed to want some other big thing that would be irrefutable. But Jesus would not give one to them because they had already rejected Him out of unbelief.
Jesus refuses to give His opponents a sign and instead warns them of judgment to come (39-45). Jesus’ response can be subdivided into several points: a rejection of a sign now but a future sign to give them another opportunity to believe; a verdict on their wickedness and a warning of judgment, and a sentence on them for their unbelief.
Also, in His response Jesus simply identified these people as a wicked and adulterous generation. No sign would be given to them---not the kind they wanted anyway.
So His point is that a willful and rebellious people do not really believe, but they do demand a spectacular sign. They have made up their minds about Jesus, and it would take something really big to change their minds. In another place Jesus made it clear that such people who do not believe in God’s revelation would not believe even if one came back from the dead (Luke 16:31). Their refusal to believe made them an adulterous generation, like their ancestors who killed the prophets.
But a sign would be given to them later-------a confirming sign. Jesus was telling them that they would have one more opportunity to be convinced----the sign of His resurrection would prove who He is and what His death was all about. They had rejected every other sign that Jesus had given them, so there was one more, but they would have to wait for it.
This was the sign of Jonah. Just as Jonah was in the belly of the fish three days and three nights, so the Messiah would be in the grave three days and three nights before rising from the dead (Jonah was not dead, but was as good as dead if God had not intervened).
This sign--the death and resurrection--would confirm that Jesus indeed is the Messiah, the Son of God. That is truly a miraculous sign. However, it would come later for these opponents of Jesus; for they were the ones who were plotting to kill Him. And they would succeed in their opposition to Jesus by seeing Him crucified. Thus, the “sign” that they wanted would come from their own crime against Him. They would be guilty of His death. But it was an opportunity that would come later; that they might then believe.
“I offer you my heart, LORD God, and I trust you.
Show me your paths and teach me to follow; guide me by your truth and instruct me.
You keep me safe, and I always trust you.” Psalms 25: 1,2a,4,5 CEV