The rock in the church is supposedly where Jesus Christ prayed before his arrest.

Church of All Nations

The Church of All Nations, also known as the Church or Basilica of the Agony, is a Roman Catholic church located on the Mount of Olives in Jerusalem, next to the Garden of Gethsemane. It enshrines a section of bedrock where Jesus is said to have prayed before his arrest. (Mark 14:32-42)

• http://en.wikipedia.org/wiki/Church of All Nations