The paucity of my religious knowledge

So, this other work I do then, slight change for Monday:
Knew about UK – “late may bank holiday” or summat, isn’t it? What used to be Whitsun – which I never knew what that was. But. US Memorial Day.
Pentecost tho’? Why the Scandis celebrating that?
Pentecost is one of the Great feasts in the Eastern Orthodox Church, a Solemnity in the Roman Rite of the Catholic Church, a Festival in the Lutheran Churches, and a Principal Feast in the Anglican Communion.
Ah, Lutherans. No Papists taking the day off tho’. Nor non-US colonials.
Shrug.