Taken from Christmas: An Historical Survey Regarding Its Origins and Opposition to It. Kevin Reed is showing the historical nature of Christmas, rooted in pagan worship, and the opposition of Christmas in the Reformation. Here Reed quotes Calvin on worship:
The mockery which worships God with nought but external gestures and absurd human fictions, how could we, without sin, allow to pass unrebuked? We know how much he hates hypocrisy, and yet in that fictitious worship, which was everywhere in use, hypocrisy reigned. We hear how bitter the terms in which the prophets inveigh against all worship fabricated by human rashness. But a good intention, i.e., an insane license of daring whatever man pleased, was deemed the perfection of worship. For it is certain that in the whole body of worship which had been established, there was scarcely a single observance which had an authoritative sanction from the Word of God.
Reed goes on to write:
Thus, Calvin’s writings on worship clearly enunciate the concept which has subsequently been called the regulative principle of worship: all modes of worship must be expressly sanctioned by God’s word, if they are to be considered legitimate. Since Christmas observances, and other ecclesiastical festivals, are not commanded in the scriptures, they fail to meet divine approval, even if there were no additional objections to them.
Further, we should note Calvin’s own pastoral practice as indicative of his convictions. The Reformer preached consecutively through books of the Bible, without regard to the ecclesiastical year. Surely if Calvin had adopted the attitude of modern Christmas-keepers, he would have felt constrained to abandon this systematic instruction of the scriptures, and deliver annual discourses from the birth narratives during the month of December. The fact that he did not comply with contemporary expectations speaks volumes.