“For prophecy never had its origin in the human will, but prophets, though human, spoke from God as they were carried along by the Holy Spirit.” focuses on fulfilled prophecies about Christ. Peter points to his eyewitness experience of the transfiguration as confirmation those prophecies are true. As a result, Peter knows that those prophecies yet to be fulfilled will happen one day.
It reads in 2 Peter 1:16–21
For we did not follow cleverly devised fables when we made known to you the power and coming of our Lord Jesus Christ, but we were eyewitnesses of His majesty. For He received honor and glory from God the Father when the voice came to Him from the Majestic Glory, saying, “This is My beloved Son, in whom I am well pleased.” And we ourselves heard this voice from heaven when we were with Him on the holy mountain. We also have the word of the prophets as confirmed beyond doubt. And you will do well to pay attention to it, as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts. Above all, you must understand that no prophecy of Scripture comes from one’s own interpretation. For no such prophecy was ever brought forth by the will of man, but men spoke from God as they were carried along by the Holy Spirit.

One reason Jesus stayed on earth for 40 days after His resurrection instead of ascending immediately into heaven was to demonstrate to His followers that He truly was alive. After all, they knew the Roman authorities had put Jesus to death, and that His body had been taken down from the cross and sealed in a tomb. But life after the tomb was unfathomable. As Jesus appears to the disciples in various miraculous ways, they are given a glimpse of something more than any heavenly or political salvation. Jesus’ life with them after the rock is rolled away becomes a revelation of what he forged in 33 years of fleshy life. He was always drawing them and us into communion with God. Jesus resurrected life he pours out who He is and reveals to us what has been born in that tomb, pentecostal beings, a confounding community. Perhaps most of all, Jesus reveals that salvation was never a place but a way. Through Jesus, we will never be without God, and God will never be without us.