The very facts that demonstrated Jesus' authenticity as the Messiah were a scandal to many of the Jews - but others understood and believed.
We are told that Jesus "marveled" at the pathetic unbelief of the people of Nazareth. How could the omniscient Son of God marvel at anything? Would He marvel at us?
Jesus' attesting signs while on earth also speak of His present power to provide "grace to help in time of need."