Brumalia

Brumalia were heathen festivals among the ancient Romans, said to have been instituted by Romulus in honor of Bacchus. They were celebrated twice a year, on the twelfth day before the Kalends of March, and the eighteenth before the Kalends of November. Among the early Christians Brumnalia were sometimes observed, according to Tertullian, who records it to their shame; but these are by some considered the celebration of the winter solstice, from bruma, winter. By the council of Trullo (A.D. 692)

Christians were prohibited from attending the Brumalia on pain of excommunication.