Matthew 12:38 Then some of the scribes and Pharisees answered him, saying, "Teacher, we wish to see a sign from you." 39 But he answered them, "An evil and adulterous generation seeks for a sign, but no sign will be given to it except the sign of the prophet Jonah. 40 For just as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth. 41 The men of Nineveh will rise up at the judgment with this generation and condemn it, for they repented at the preaching of Jonah, and behold, something greater than Jonah is here. 42 The queen of the South will rise up at the judgment with this generation and condemn it, for she came from the ends of the earth to hear the wisdom of Solomon, and behold, something greater than Solomon is here.
Let's start with the last verses of this passage of Scripture. Jesus' presence among the Scribes and Pharisees was greater than the preaching of Jonah to the people of Nineveh and greater than Solomon.
Who did Jesus claim to be? He called God His Father, making Himself equal with God (John 5:18). He said, "Before Abraham was, I am." "I Am" is the name God gave of Himself to Moses in Exodus 3:14 (John 8:58). In John 10:33 the Jews were going to stone Jesus because He was calling Himself God. Jesus claimed to be the fulfillment of Isaiah 61:1-2 in Luke 4:16-21. Jesus was God come as a man (John 1:1-3, 14). Can you imagine the Creator of the Universe walking and teaching among us, doing miracles, raising the dead, over-ruling the laws of nature and we ask Him for a sign to prove who He is?
Jesus knew the corruptness of people, "An evil and adulterous generation seeks for a sign...". Jesus knew that if people world not believe Moses and the Prophets (God's Word), they wouldn't believe the sign He was willing to give them (Luke 16:29-31). Jesus did give them the sign of Jonah who was three days and nights in the belly of the great fish. The sign was Jesus three days and nights dead and then raised from the dead. The Apostle John tells us the sign Jesus gave to the Jews who asked Him to validate His authority, "Destroy this temple and in three days I will raise it up." John tells us the temple He was referring to - His body (John 2:18-22).
The proof, that Christianity is true, is the resurrection of Jesus from the dead. Jesus told His disciples ahead of time that He would suffer, be killed and raised from the dead on the third day (Luke 9:21-22). When the ladies went to prepare Jesus body for burial and found the tomb empty, an angel reminded them what Jesus had told them earlier - that He would rise from the dead on the third day (Luke 24:1-12). The Scriptures are true because Jesus rose from the dead just as He said He would.
"Prove God is real. Prove Jesus is God. Prove the Scriptures are reliable." The proof: Jesus rose from the dead on the third day just as He said He would. Let's take Jesus at His word and live the abundant and eternal life He has given us each and every day!