Church Counciles, Creeds and Feast Days

Regarding the Church Counciles and Church Creeds i.e. the Council of Chalcedon 451AD and the earlier Athanasian Creed. Both the Church counciles and the Church creeds [also the Reign of Emperor Charlemagne] would consider the new modern Feast day interpretation an error by the combining of Holy Week (Jesus Christ) with The Feast of Pentecost…