What is the X in X-mas?
c.1200, ancient Italian goddess of the moon, patroness of virginity and hunting, later identified with Greek Artemis, and through her with eastern goddesses such as Diana of Ephesus. The name is earlier Diviana, from *diw-yo-, from PIE root *dyeu- "to shine" (see Zeus).
so called by the Romans; called Artemis by the Greeks, the "great" goddess worshipped among heathen nations under various modifications. Her most noted temple was that at Ephesus. It was built outside the city walls, and was one of the seven wonders of the ancient world. "First and last it was the work of 220 years; built of shining marble; 342 feet long by 164 feet broad; supported by a forest of columns, each 56 feet high; a sacred museum of masterpieces of sculpture and painting. At the centre, hidden by curtains, within a gorgeous shrine, stood the very ancient image of the goddess, on wood or ebony reputed to have fallen from the sky. Behind the shrine was a treasury, where, as in 'the safest bank in Asia,' nations and kings stored their most precious things. The temple as St. Paul saw it subsisted till A.D. 262, when it was ruined by the Goths" (Acts 19:23-41)., Moule on Ephesians: Introd.