Theodora Polamalu, Paisios Polamalu and Troy Polamalu. "Kala Christougena!" said Steelers safety Troy Polamalu. That's Greek for "Merry Christmas!" Mr. Polamalu and his wife, Theodora, actually celebrated Christmas 13 days ago, but they keep the same Orthodox traditions as those who observe today. Most Orthodox celebrate on Dec. 25, but many Slavic churches tie liturgy to the old Julian calendar, which is 13 days behind the Gregorian calendar. The Greek Orthodox Church and some others have adopted the Gregorian calendar -- except at Easter.