Ex. Today is also the Commemoration of St. Alexander Nevsky, the Rightly Believing Prince of Novgorod.
http://castrorum.blogspot.ro/2006/11/thanksgiving.html

Some maintain that the Orthodox—the rightly believing Christians—asked John to write about Christ’s eternal generation in order to refute certain heretics who had already begun to teach that the Saviour was merely a man.
http://www.chrysostompress.org/explanation_john_preface.html