http://www.humanreligions.info/tags/sun_worship.html
Human Truth Foundation pages (9):
The Birth of Jesus and the Christmas Story: Pagan and Unhistorical, in the following sections:
The True Meaning of Christmas: Paganism, Sun Worship and Commercialism, in the following sections:
Christians Against Christmas: 4. About Christmas
When Was Jesus Born? What Year, and Which Day?
Sun Worship and the Founding of World Religions Such as Judaism and Christianity (Astrotheology): 1. The Cause of All Religion
What Causes Religion and Superstitions?: 5.5. The Stars and the Sun, Resurrection and Rebirth
International Date Format (ISO 8601) and Time Measurements: 4. What Year Was Jesus Christ Born?
Not from the Human Truth Foundation, but still relevant (1):