Jesus was palling around with three disciples (Peter, James and John) while hiking a mountain, when suddenly Moses and Elijah appeared in a blinding radiance around Jesus. Then the voice of God called him Son...so all and all, it was a pretty significant trundle.
This event in Christianity is referred to as the "Transfiguration of Jesus", and it has been interpreted several different ways. Some believe that the transfiguring is the revealing of the divine to human sense perception. Another is the revelation that Jesus is the Son of God. Another still is that this really tees things up for a Crucifixion/Resurrection.
The Transfiguration event ranks much higher in the Eastern Orthodox greatest hits, but the Western church honors it through a number of celebrations.
One of the hypothesized locations for the Transfiguration is at Mount Tabor, where there are currently two churches (Roman Catholic and Eastern Orthodox) dedicated to Transfiguration on the summit.
