The Romans ruled over the British Isles for nearly four centuries. During this time some Roman concepts many have crept into Celtic and Byronic traditions like Samhain. The Roman goddess Pomora might account for the prevalence of apples (both of the caramel-coated and bobbing variety) and seeds in Halloween traditions. The Roman festival of Parentalia, which dealt with interactions between the living and the dead and was punctuated by a ceremony to exorcise troublesome spirits from the home, shares an understanding of the nature of pesky spirits and the necessity to confuse or banish them from the earthly realm.
It is through contact with the Roman Empire, which would adopt Christianity as its state religion, that we see Christianity’s attempt to de-paganize Samhain. The Christianization of Samhain actually is a function of converting the aforementioned festival Parentalia to a less pagan holiday. Parentalia was originally celebrated in May. In a move to replace the pagan overtones of the holiday Pope Boniface IV use the day to reconsecrate the Pantheon to the Christian god. This made Parentalia into a Christian day of remembrance. Centuries later Pope Gregory III later changed the date of remembrance to November 1 when he dedicated St. Peter’s Basilica to the entire host of saints. This became All Saints Day, a major holiday in the Roman Catholic tradition.
The day before All Saint’s Day became All Hallow’s Eve, a holiday widely celebrated throughout all of Christendom by the 9th century. Samhain and Nos Calan Gaeaf got sucked into early Christianity in this way.
