Elijah and Moses are alive?
Clothes dazzling brighter than bleach?
Clouds that speak?
Peter, James, and John must have been speechless - well, except for Peter, who said something even though he didn't know what to say.
The transfiguration is unique among the many events recorded in the Gospels. It assures us that we indeed live beyond our earthly lives - not by telling us so, but by showing us! The patriarchs and prophets are indeed "gathered to their people" (Gen. 25:8, 25:17, 35:29, 49:33, etc.). It also shows us that they are able - when it's for God's purposes - to return to earth, which helps us to understand other events in scripture better (Rev. 11:6-12).
Most importantly, a voice from the cloud commands all present to listen to Jesus. We know this is the voice of God the Father because He calls Jesus His Son. So all those claims Jesus makes, all His teaching, are to be taken as, well, Gospel! We can't pick and choose what we want to obey and reject others.
I always relate to Peter, though. Like Peter, I tend to speak before I think; and the second it leaves my mouth, I realize how dumb it was, or worse yet, I slowly begin to realize it. At least some people explain my misstatement to me when I never caught it. But when I look at Peter in Acts 2:14-41 - WOW! 3,000 people responded to Peter's words that day. If Jesus could train up my kindred Peter, there may be hope for me. I know that time hasn't come yet because I'm still not sure what was wrong with what Peter said in Mk. 9:5.
Peter gives me hope in his failures as well as in his later victories. Peter may have failed a few times, but it's his endurance that inspires. A few weeks ago in this blog, we discussed Peter speaking both with heaven-sent insight and words from Satan. In Acts we see Peter moving thousands to repentance. Are you like Peter - like me? Will you retreat in isolation and shyness because of embarrassment from past mistakes, or will you forge ahead and keep speaking, knowing that eventually, you'll bring more to wisdom than you alienate? Speak up and you'll eventually speak truth.