In the Christian context: by “mystery,” we do not mean merely that which is baffling and mysterious, an enigma or insoluble problem. On the contrary, a mystery is something that is revealed for our understanding, but which we never understand exhaustively because it leads into the depth or the darkness of God. The eyes are closed—but they are also opened.t
The mystery is not unknown—it is endless.
The sign for the mystery world is this: if I do not feel a sense of joy in God’s creation, if I forget to offer the world back to God with thankfulness, I have advanced very little upon the Way. I have not yet learnt to be truly human. For it is only through thanksgiving that I can become myself.
Based on Metropolitan Kallistos (Ware) of Diokleia
A shot from the holy altar of the katholikon (main church) of Vatopedi