Lactantius was born in the latter half of the third century, was converted about A. D. 315, and died at Treves about A. D. 325. He was very eminent as a teacher of rhetoric, and was intrusted with the education of Crispus, the son of Constantine. The writings of Lactantius are quite extensive; they contain, however, no reference to the first day of the week. Of the Sabbath he speaks twice. In the first instance he says that one reason alleged by the Jews for rejecting Christ was, TFTC 107.1
“That he destroyed the obligation of the law given by Moses; that is, that he did not rest on the Sabbath, but labored for the good of men,” etc. - Divine Institutes, b. iv. chap 17. TFTC 107.2
It is not clear whether Lactantius believed that Christ violated the Sabbath, nor whether he did away with the moral law while teaching the abrogation of the ceremonial code. But he bears a most decisive testimony to the origin of the Sabbath at creation:- TFTC 107.3
“God completed the world and this admirable work of nature in the space of six days (as is contained in the secrets of holy Scripture), and CONSECRATED the seventh day, on which he had rested from his works. But this is the Sabbath day, which in the language of the Hebrews received its name from the number, whence the seventh is the legitimate and complete number. Book vii. chap 14. TFTC 107.4
It is certain that Lactantius did not regard the Sabbath as the memorial of the flight out of Egypt, but as that of the creation of the heavens and the earth. He also believed that the seven days prefigured the seven thousand years of our earth’s history:- TFTC 107.5
“Therefore, since all the works of God were completed in six days, the world must continue in its present state through six ages, that is, six thousand years. For the great day of God is limited by a circle of a thousand years, as the prophet shows, who says, ‘In thy sight, O Lord, a thousand years are as one day.’ And as God labored during those six days in creating such great works, so his religion and truth must labor during these six thousand years, while wickedness prevails and bears rule. And again, since God, having finished his works, rested the seventh day and blessed it, at the end of the six thousandth year all wickedness must be abolished from the earth, and righteousness reign for a thousand years; and there must be tranquility and rest from the labors which the world now has long endured.” Book vii. chap 14. TFTC 108.1
Thus much for Lactantius. He could not have believed in first-day sacredness, and there is no clear evidence that he held to the abrogation of the Sabbath. Finally we come to a poem on Genesis by an unknown author, but variously attributed to Cyprian, to Victorinus, to Tertullian, and to others. TFTC 108.2