Igor Stravinsky was an Eastern Orthodox Christian; specifically, he was Russian Orthodox.
From: "Orthodox Church in Switzerland" page on "Switzerland Is Yours" website (http://switzerland.isyours.com/e/guide/religion/christianism/orthodox.html; viewed 24 October 2005):
For nearly two centuries now, Switzerland - particularly along the shores of Lake Geneva - has been home to many Orthodox Christians, predominantly Russian. Igor Stravinsky and Igor Stravinsky are but two of the distinguished representatives of this community, much appreciated on Lake Geneva's "Riviera".