Stop your calls, please. We have a winner!
Mormons are not Orthodox Christians.
Or very nearly, IMHO. Of course, Mormons might say I'm not orthodox. Heck, even the "Orthodox" say catholics are not orthodox! And Protestants say all manner of things.
I'd go with "Nicene Creed and Chalcedonian Definition Subscribing" as a bulky and cumbersome effort to take both "Christian" and "Orthodox" out of the "they mean what I SAY they mean" pile and put them in the "more or less objectively determinable" pile.
But maybe that's just me.