I found the medalion with the words and pronounce these words (Blessed be Kerah) standing in front of the statue, but nothing happens. I tried standing close to it and far from it, but it doesn't react to anything! I'm just blocked there! Help!

Elfia,
The words you are supposed to use are the first (latin) translation on the medallion (ie Sanctus Kerah from memory).
Watch out for Drop Bears.

Another thought... check your journal... it should show the exact words to type to the statue (while in talk mode)~

good luck,
dh