As Jesus and the three disciples, Peter, James & John, were returning from the mountain, Jesus ordered them not to tell anyone what had happened there until He had risen from the dead.
But Jesus also trusted them with some additional details, saying that Elijah had already come, and they did to him "everything they wished" (Mk. 9:13). Jesus was referring to John the Baptist, who was beheaded, and was "the Elijah who was to come" (Mt. 11:14).
Today, we have the full scripture, Christians have the Holy Spirit to reveal its meaning to us, and we have godly pastors and teachers to help us make sense of it all. There remains no excuse for rejecting God because He has called His people in each generation to help us to find Him. No more secrets - nothing stays on the mountain. Christ's work on the cross to overcome death and separation from God has been completed, and the gift of grace is there for the asking.
Won't you join in the journey of full knowledge by believing what was once secret, what is now an "open secret", that Jesus Christ is the Son of God, born of a virgin, who gave His life so that our fellowship with God, lost since the fall of Adam, would be restored?
As Zig Ziglar said, "See you at the top."