Source: William L. Gildea, "Paschale Gaudium," The Catholic World, 58 (March, 1894), 809. [FRS No. 100.]
"The church took the pagan philosophy and made it the buckler of faith against the heathen. She took the pagan, Roman Pantheon, temple of all the gods, and made it sacred to all the martyrs; so it stands to this day. She took the pagan Sunday and made it the Christian Sunday. She took the pagan Easter and made it the feast we celebrate during this season.
Sunday and Easter day are, if we consider their derivation, much the same. In truth, all Sundays are Sundays only because they are a weekly, partial recurrence of Easter day. The pagan Sunday was, in a manner, an unconscious preparation for Easter day. The Sun was a foremost god with heathendom. Balder the beautiful, the White God, the old Scandinavians called him. The sun has worshippers at this hour in Persia and other lands. "Some of you," says Carlyle, "may remember that fancy of Plato’s. A man is kept in some dark, underground cave from childhood till maturity; then suddenly is carried to the upper airs. For the first time he sees the sun shining in its splendor overhead. He must fall down, says Plato, and adore it." There is, in truth, something royal, kingly about the sun, making it a fit emblem of Jesus, the Sun of Justice. Hence the church in these countries would seem to have said, "Keep that old, pagan name. It shall remain consecrated, sanctified." And thus the pagan Sunday, dedicated to Balder, became the Christian Sunday, sacred to Jesus. The sun is a fitting emblem of Jesus. The Fathers often compared Jesus to the sun; as they compared Mary to the moon, the beautiful moon, the beautiful Mary, shedding her mild, beneficent light on the darkness and night of this world—not light of her own; no Catholic says this; but—light reflected from the sun, Jesus."
Source: Franz Cumont, The Mysteries of Mithra, trans. by Thomas J. McCormack (reprint: New York: Dover Publications, Inc., 1956), pp. 167, 191. [FRS No. 95.]
[p. 167] Each day in the week, the Planet to which the day was sacred was invoked in a fixed spot in the crypt; and Sunday, over which the Sun presided, was especially holy…
[p. 191] [The worshippers of Mithra] held Sunday sacred, and celebrated the birth of the Sun on the 25th of December.
Source: H. G. Wells, The Outline of History, pp. 499, 512, 513. Copyright 1920 and 1921 by The Macmillan Company, New York, and by H. G. Wells. Used by permission of Prof. G. p. Wells. [See FRS No. 110.]
[p. 499] The observance of the Jewish Sabbath, again, transferred to the Mithraic Sun-day, is an important feature of many Christian cults…
[p. 512] During this indefinite time [the 1st and 2d centuries] a considerable amount of a sort of theocrasia seems to have gone on between the Christian cult and the almost equally popular and widely diffused Mithraic cult, and the cult of Serapis-Isis-Horus. From the former it would seem the Christians adopted Sun-day as their chief day [p. 513] of worship instead of the Jewish Sabbath.
Source: H. Lamer, "Mithras," Wo¬rterbuch der Antike (2d ed.; Leipzig: A. Kröner, 1933). Used by permission. German.
Concerning the power of the Mithras cult we still have evidence in the fact that it is not the Jewish in the fact that it is not the Jewish Sabbath that is the sacred week-day, which Christianity, coming out of Judaism, had nearest at hand, but Sunday, dedicated to the Sun-god Mithras.
Source: Walter Woodburn Hyde, Paganism to Christianity in the Roman Empire, pp. 257, 258, 260. Copyright 1946 by University of Pennsylvania Press, Philadelphia. Used by permission.
[p. 257] Modern Christians who talk of keeping Sunday as a "holy" day, as in the still extant "Blue Laws" of colonial America, should know that as a "holy" day of rest and cessation from labor and amusements Sunday was unknown to Jesus… It formed no tenet of the primitive Church and became "sacred" only in course of time. Outside the Church and became "sacred" only in course of time. Outside the Church its observance was legalized for the Roman Empire through a series of decrees starting with the famous one of Constantine in 321, an edict due to his political and social policies rather than, as Eusebius thought, to religious ones. For he took the day not because of the Christian custom of meeting then to commemorate the Resurrection but from "the venerable day of the Sun" (Mithra), and especially in order to give to Roman slaves respite from labor which their Semitic brothers had enjoyed for centuries. So much confusion in identifying Sunday and the Sabbath has been inherited by Britain and America through Puritan influence that it seems well to recapitulate the well-known facts…
As the Jewish element in the Church waned the Christians came to feel the need of a fixed day for [p. 258] meetings to replace the Sabbath. Then Sunday, like other pagan festivals such as Christmas, came gradually into being, first as a fit day for worship and later one for rest…
[p. 260] Parallel to the Church movement … but independent of it another had been developing in the State which after an obscure past culminated in Constantine’s decree of 321 when the observance of the "day of the Sun" was imposed on the Empire, a decree marking an epoch in the history of Sunday as the beginning of both civil and later of ecclesiastical legislation. Now dies Solis , sacred in various solar cults and notably in Mithraism, was to play a role as the Christian Sunday as Christmas did a little later.