Lentorama 2021: Take Your Holiday to Go

Day 10: Trinity Sunday

Occurring on the first Sunday after Pentecost (for Western Christians; it's on the Sunday of Pentecost for Eastern Christians), Trinity Sunday celebrates the doctrine of the Holy Trinity. While it got its feast day in the 14th century, it was celebrated well before then. Pope Alexander II refused to create a specific feast in the 11th century, but allowed local feast to continue, so it was likely being celebrated for some time before then.

The basis for the feast comes from an office that was created in response to the Arian heresy, which cropped hundreds of years before Alexander II. How it went from something observed every Sunday to an annual feast day isn't clear, but one theory is that Thomas Beckett, after being made Archbishop of Canterbury, decreed that the date of his ordination should be a feast day in honor of the Holy Trinity.

Johann Sebastian Bach composed a number of cantatas for the holiday, three of which are still known  (BWV 129, 165 and 176). A fourth (BWV 194) wasn't created for the day but was later played on it.