Contrary to popular misconceptions, All Saints Day and its vigil, Halloween, are not the same as the pagan feast known as Samhain. The feast of All Saints developed independently among Christian churches within the territory of the later Roman Empire.
Halloween is merely the vigil of the feast of All Saints -- hence, All Hallows Eve.
Samhain, meanwhile, was theoretically a festival of those pagans in Celtic regions outside the Roman Empire, specifically Ireland, about which almost nothing is known prior to the 12th century AD.
The two feasts seem to share a common date, but beyond that, their provenance is quite different.
If you run into someone who insists that Halloween is actually the pagan celebration of Samhain, ask them to provide a primary source reference demonstrating that point. They will struggle to do so because the earliest extant literary references to the pagan festival don't occur until the Middle Ages, and much of what passes for descriptions of pagan Samhain traditions and practices are nothing more than fanciful modern imaginings. Ronald Hutton, writing in
The Stations of the Sun: A History of the Ritual Year in Britain offers the following about traditional pagan practices during Samhain according to sources from the 10th through 12th centuries:
In Serglige Con Culaind, which exists in a twelfth-century version, it is stated that the feis of the Ulaid (Ulstermen) lasted ‘three days before Samuin and the three days after Samuin and Samuin itself. They would gather at Mag Muirthemni, and during these seven days there would be nothing but meetings and games and amusements and entertainments and eating and feasting.” These activities (together with a great deal of boasting and brawling) are precisely those portrayed at the feis in this and other accounts of it. No doubt there were religious observances as well, but none of the tales ever portrays any, and a text like Sanas Chormaic, which is so informative on Beltane, furnishes nothing for the winter festival. [Hutton: The Stations of the Sun]
It should be noted that the above passage was written by a scholar who is largely sympathetic to the pagan side of the argument, but is honest enough to admit that there is no ancient evidence to support it. Indeed, the holiday described in the 12th century source above seems to have more affinity to American Thanksgiving, with its feasts, games and brawling than All Hallows Eve.
Meanwhile, there is considerable ancient literary evidence to support the Catholic feast of All Saints and All Hallows Eve. The feast was originally celebrated on various dates in various churches as early as the 4th century AD, and began to be officially established on November 1 in many places throughout Europe by the early Middle Ages.
Here is a passage from a homily of Saint Bede's written in the early 8th century:
"Today, beloved, we celebrate in the joy of one solemnity, the festival of All Saints, in whose companionship the heaven exults; in whose guardianship the earth rejoices; by whom triumphs the Holy Church is crowned; whose confession, as braver in its passion, is also brighter in its honor—because while the battle increased, the glory of them that fought in it was also augmented. And the triumph of martyrdom is adorned with the manifold kind of its torments, because the more severe the pangs, the more illustrious also were the rewards; while our Mother, the Catholic Church, was taught by her Head, Jesus Christ, not to fear contumely, affliction, death, and more and more strengthened—not by resistance, but by endurance—inspired all of that illustrious number who suffered imprisonment or torture, with one and equal ardor to fight the battle for triumphal glory.
"O truly blessed Mother Church! so illuminated by the honor of divine condescension, so adorned by the glorious blood of triumphant martyrs, so decked with the inviolate confession of snow white virginity! Among its flowers neither roses nor lilies are wanting. Endeavor now, beloved, each for yourselves, in each kind of honor, to obtain your own dignity—crowns, snow white for chastity, or purple for passion. In those heavenly camps, both peace and war have their own flowers wherewith the soldiers of Christ are crowned."
The rest of this sermon may be read here.
As for the date of November 1, here is a quote from the
Chronicon of Sigebert of Gembloux, detailing the official movement of All Saints Day to November 1 throughout the Holy Roman Empire as of the year AD 835:
DCCCXXXV: Monente Gregorio Papa et omnibus episcopis
assentientibus, Ludovicus Imperator statuit, ut in Gallia et Germania
festivitas Omnium Sanctorum in kalendis Novembris celebrarentur, quam Romani ex
instituto Bonefacii Papae celebrabant.
Forgive
my rough translation: 835 AD: Following the instruction of Pope Gregory [IV] and the assent
of all the bishops, Emperor Louis [the Pious] established that in France and Germany the
feast of All Saints would be celebrated on the first of November, when the
Romans celebrate following the custom established by Pope Boniface [IV].
See the original here.
Writing from a more syncretist point of view not unsympathetic to the pagan side, Alexei Kondratiev says the following, which gives a plausible explanation of why, in Medieval times, those still holding semi-pagan beliefs may have consolidated their beliefs about the dead around All Saints/Souls day, following the lead of the Church:
“Whatever the specific elements had been that determined the proper date of the end-of harvest honoring of the dead in various places, by the ninth and tenth centuries the unifying influence of the Church had led to concentrating the rituals on November 1st and November 2nd. The first date was All Hallows, when the most spiritually powerful of the Christian community's dead (the Saints) were invoked to strengthen the living community, in a way quite consistent with pre-Christian thought. The second date, All Souls, was added on (first as a Benedictine practice, beginning ca. 988) as an extension of this concept, enlarging it to include the dead of families and local communities. Under the mantle of the specifically Christian observances, however, older patterns of ancestor veneration were preserved.” [Kondratiev: Samhain - Season of Death and Renewal]
This is an honest assessment that seems to capture quite well the actual history behind All Saints Day / Halloween and its relationship to co-existing pagan death rituals and ancestor worship.
As Catholics, we have not done a particularly good job informing the modern culture of the Christian meaning behind All Hallows Eve. As a result, we have ceded the field to the purveyors of popular culture who have turned the feast into a celebration of monsters, gore and neo-paganism. The correct response, in my opinion, is not to opt out completely, but to bring the holiday back to its uniquely Christian roots. Doing so will not only serve to dispel myths propagated by an increasingly hostile secular society, but will also help Catholics young and old to be inspired by the stories of "that illustrious number who suffered imprisonment or torture, with one and equal ardor to fight the battle for triumphal glory."
One idea I particularly like is to read more about the lives of the saints during this time of year, particularly with your kids.
Here is a list of about 40 novels and short biographies of a variety of Catholic saints and heroes, courtesy of The Young Catholic's Bookshelf.
Or, if that's too much for you, try reading this one new book about the lives of the early martyrs drawn from the most trustworthy eye-witness sources:
I Am A Christian: Authentic Accounts of Christian Martyrdom and Persecution from the Ancient Sources.
Or, if you'd prefer, here is an inexpensive booklet which will allow you to celebrate All Hallow's Eve like a traditional Catholic (imagine that!).
All Hallow's Eve Prayers and Devotions is a new booklet by our friends at Ancilla Press that combines Celtic, English, and Latin traditions in a unique format. It provides adults and children with an unashamedly Catholic and historically authentic way to celebrate the beginning of Hallowtide, and includes the full version of "Black Vespers", an old Breton tradition for the afternoon of Halloween, three prayers against evil spirits, witchcraft, and spells, and more.
Click here to order a copy or to find out more.