The Christian Origins of Halloween:"Halloween" is a name that means nothing by itself. It is a contraction of "All Hallows Eve," and it designates the vigil of All Hallows Day, more commonly known today as All Saints Day. ("Hallow," as a noun, is an old English word for saint. As a verb, it means to make something holy or to honor it as holy.) All Saints Day, November 1, is a Holy Day of Obligation, and both the feast and the vigil have been celebrated since the early eighth century, when they were instituted by Pope Gregory III in Rome. (A century later, they were extended to the Church at large by Pope Gregory IV.)
The Pagan Origins of Halloween:Despite concerns among some Catholics and other Christians in recent years about the "pagan origins" of Halloween, there really are none. The first attempts to show some connection between the vigil of All Saints and the Celtic harvest festival of Samhain came over a thousand years after All Saints Day became a universal feast, and there's no evidence whatsoever that Gregory III or Gregory IV was even aware of Samhain.
ShareIn Celtic peasant culture, however, elements of the harvest festival survived, even among Christians, just as the Christmas tree owes its origins to pre-Christian Germanic traditions without being a pagan ritual. (Read more.)