St. Patrick preaches to the Celtic High King of Ireland. Stained glass, St. Joseph's Catholic Church, Macon, GA. (Photo credit: Wikipedia)
St. Patrick kept Saturday as the sabbath. During the first century the Roman Empire did not extend into Scotland and Ireland. The Roman Empire made several attempts to conquer Scotland to no avail. The Romans eventually build a wall between Scotland and England called Adrian Wall. Remnants of that wall are still present today. Therefore the beliefs of the early Catholic Church did not get infiltrated into Scotland and Ireland until must later in History. Below are 4 Historical references proving that Saturday not Sunday was kept as the day of worship in Ireland and Scotland.
1) Historian A. C. Flick writes:
“The Celts used a Latin Bible unlike the Vulgate, and kept Saturday as a day of rest, with special religious services on Sunday.”
The Rise of the Medieval Church, page 237, Flick.
2) “It seems to have been customary in the Celtic churches of early times, in Ireland as well as Scotland, to keep Saturday, the Jewish Sabbath, as a day of rest from labor. They obeyed the fourth commandment literally upon the seventh day of the week.”
The Church in Scotland, page140, James C. Moffatt, D.D.
3) “In this latter instance they seemed to have followed a custom of which we find traces in the early monastic church of Ireland by which they held Saturday to be the Sabbathon which they rested from all their labours.”
Adamnan Life of St. Columba, page 96), W.T. Skene
4) From the Catholic historian, T. Ratcliffe Barnett, on the Catholic queen of Scotland: “In this matter the Scots had perhaps kept up the traditional usage of the ancient Irish Church WHICH OBSERVED SATURDAY INSTEAD OF SUNDAY AS THE DAY OF REST.”