Supporting Evidence for Calculation Theory
The dismissal of Calculation Theory for determining the date of the Christmas feast since its conception has been a pastime of the popular consensus. History of Religions Theory proponents have convinced many people that the feast of Christmas is directly related to pagan traditions or intra-doctrinal disputes within the frameworks of Christianity. The proponents of HRT, such as Susan Roll in her book Toward the Origins of Christmas, assert that because of the CT proponents supported evidence “that more questions have perhaps been raised than have been answered by the hypothesis.” HRT proponents often conclude that CT theorist evidence lacks any hard evidence; notwithstanding, CT theorists continue to produce more evidence from primary sources to produce a positive position. C.Philipp E. Nothaft explains in his defense of CT theory that “HRT is nowadays used as the default explanation for the choice of 25 December as Christ’s birthday, few advocates of this theory seem to be aware of how paltry the available evidence actually is.”
The History of Religion theory on the date and causation of the Christmas feast has several popular sub-theories. The first theory is the idea that Christmas was created as a “deliberate distraction for Roman Christians from the feast of Saturnalia.” Roll acknowledges that this cannot be true as the Saturnalia feast was celebrated from the seventeenth of December to the twenty-third.
Another concept is the idea of Sun worship and its connection to the birth of Christ. Herman Usener, in his work Das Weihnachtsfest, created a thesis that Christians attempting to keep interest in their new religion adapted their customs to pagan traditions in regards to Natalis Solis Invicti. Usener argues that Christmas did substitute for the feast of Natalis Solis Invicti by providing evidence that a notation made in the 354 Chronograph, the De Solstitiis. Louis Duchesne, Calculations Theorist, would refute Usener’s argument on the basis that it didn’t account for the fact that the celebration of Christmas was celebrated in the Eastern Roman Empire on January 6th, the Epiphany date. Furthermore, as Roll notes, Joseph “Blotzer suggests that a pure substitution of Christmas for Nalalis Solis Invicti was unlikely since the sun festival has lost much of its importance by mid-fourth century.” Nothaft examining the subject indicates that HRT theorists lack evidence to support that fourth century Christians would adopt pagan traditions due to their “patristic disdain for paganism.”
Bernard Botte would attempt to counter Duchesne’s refutation point of the January 6th date from Usener’s thesis by admitting the evidence of the 354 Chronograph that listed Christmas and not Epiphany as the liturgical year started at Christmas by 336. In Botte’s view, the Christmas feast was in competition to the Pagan feasts as it “was introduced to draw away the faithful from the pagan solemnities.” However, Botte’s assertion would also not hold up to the Nothaft critique.
Nothaft answers the most challenging question posed by HRT theorist explained by a question raised by Roll and whether “ordinary Christians in the and fourth centuries much interested in calculations with symbolic numbers in fantasy-combinations?” As Nothaft explains, “Thanks to the meticulous research of Venance Grumel, August Strobel and others, it has become increasingly clear that chronological and computistical speculation played a central role in Christian thought from an early stage onwards.” The two early sources that provide evidence for Nothaft’s assertion are the paschal table of Hippolytus, which dates around 222 A.D. and De pascha computus written in 243. Both sources indicate Christian interest in calculating dates around the theme of the life of Jesus Christ.
By establishing the precedent for early Christians conducting calculations, it must be expressed that as historians and theologians look to establish a thesis on why and when the Christmas feast was established, they must appeal to the desires of early Christians instead of their own bias.
 Susan Roll, Toward the Origins of Christmas (Netherlands: Kok Pharos Publishing House. 1995), 105.
 C. Philipp E. Nothaft, “Early Christian Chronology and the Origins of the Christmas Date,” Questions Liturgiques: Studies in Liturgy Vol. 94 (2013): 248.
 Roll, 88.
 Ibid, 131.
 Ibid, 133.
 Ibid, 134.
 Nothaft, 248.
 Roll, 139-40.
 Ibid, 143.
 Ibib, 105.
 Nothaft, 252.