http://history.enotes.com/history-fact-finder/religion/what-criteria-for-sainthood
says
"Criteria for sainthood or canonization (being declared holy by the Roman Catholic Church and the Eastern Orthodox Church) are leading a holy life, conducting miracles, and suffering or sometimes dying because of one's faith (martyrdom). The Roman Catholic Church keeps a list of saints. However, some names were dropped from the list in 1969 because inclusion could not be justified by history."

http://en.wikipedia.org/wiki/Cyril_of_Alexandria

"His writings and his theology have remained central to tradition of the Fathers and to all Orthodox to this day."