Destroy this temple

“Then the Jews demanded of Him, ‘What miraculous sign can You show us to prove Your authority to do all this?’ Jesus answered them, ‘Destroy this temple, and I will raise it again in three days.’” John 2:18-19
The Pharisees and teachers of the law were big on authority and qualifications. So when Jesus, who was to them just an unknown carpenter from the north, caused a big ruckus in the temple (John 2:14-16), they pounced. Many times throughout the gospels, Jesus is asked to give a miraculous sign to prove Himself (sometimes even after performing a miracle). In every instance, of course, He refuses. Instead, He points to the most miraculous sign of all, which is to come: His resurrection from the dead.
It is the same in this passage. John 2:21 leaves us in no doubt: “But the temple He had spoken of was His body.”
Jesus’ resurrection is like no-one else’s. Every other person in the Scripture who was raised from the dead, was raised by another person (Elijah, Jesus, Paul, etc.). But nobody spoke over the dead body of Jesus as He lay in the tomb. He, being God, raised Himself from the dead.
The resurrection of Jesus Christ proves that He is God. It proves that He has authority in all things.