The Orthodox believe that Christ will "come again in glory to judge the living and the dead, and his kingdom will have no end."
So we believe, that at a point in temporal history, he will come again. The dead will be raised into new bodies, and together with the living, we will be in the presence of God. Everything will be restored - a new earth - for eternal life.
When? We do not know. People think the book of revelation describes when; but it does not. It metaphorically speaks of catastrophes that have been happening throughout history and will continue to happen.
The disciples ask Jesus in Matthew 24, "what will be the sign of your coming?" Jesus says his coming is near when these things occur:
- False prophets
- Wars and rumours of wars
- Famine, pestilence, earthquakes
- Tribulation, martyrdom
- Lawlessness
- Love will grow cold
- The gospel is preached to everyone
- Great unprecedented tribulation
The thing is, most of these things have been happening since Christ came! Which means the second coming is always near. But what is near in God's terms?
The point is - the second coming will be as surprising as death. Like a flash. "For as the lightning comes as a flash from the east to the west, so will be the coming of the Son of Man."