Jesus Was Audibly Endorsed by God the Father
On two occasions, God the Father audibly spoke from heaven to Jesus and the people in hearing distance.
Immediately prior to the ministry of Jesus, large crowds gathered in the wilderness to hear the preaching from John the baptist and be baptized by him. When Jesus came to be baptized, the heavens opened up. The Holy Spirit descended on Jesus in bodily form like a dove, and God the Father spoke, "You are my beloved Son, in You I am well-pleased." Accounts of this can be found at Matthew 3:17, Mark 1:11, and Luke 3:22.
Toward the end of His earthly ministry, Jesus took Peter, James, and John up on a high mountain where Jesus was transfigured before them. In other words, He allowed some of the glory of God to show through His human body. His face shone like the sun, and His garments became radiant and exceedingly white. Old Testament prophets, Moses and Elijah appeared also and were talking with Jesus. Then a bright cloud overshadowed them, and a voice out of the cloud said, "This is My Son, My Chosen One; listen to Him!". Accounts of this can be found at Matthew 17:1-13, Mark 9:2-13, and Luke 9:28-36.
It's easy to read these versus and not grasp the real impact. God the Father spoke from heaven. There were no smoke and mirrors, no special effect. This was not a movie or a dream. If you had been one in the crowd and heard the voice of God, would you believe?