Pantokrator

The Pantokrator (Jesus as the Lord / Master) is the most famous type of Christ-icons. The hand with the teaching-guesture bears two symbols: the three fingers, which are put together, sybolize the Trinity, the two raised fingers the 2 natures of Jesus (human and divine).

The original of this icon is from the 13th century.

See also: http://en.wikipedia.org/wiki/Pantocrator