Coming from a majoritarily Christian country, I can say the celebrations taking place on New Year's eve are, and have always been completely detached from those of any religious holiday marked in any of the Christian calendars. This is why the party is on at night and focuses on the passing from the midnight hour of one year to the first day of the new year, and is celebrated by religious, agnostics, atheist, everybody else in the same way : eating, drinking, partying. More than this, many are following a series of rituals of pagan origins, related to the ancient agricultural traditions, pre-christian folklore superstitions, basically, wishes of luck, fertility, health and prosperity and casting away "evil spirits", more for esthetic purposes, their original meaning being lost. In fact, most priests are even against these celebrations. Stuff yourself with hearty foods, dance until numb, drink all night, sleep in the morning instead of going to church said no priest ever.
Neurologist and author Oliver Sacks dies at 82 (Haaretz)
from the article: What we talk about when we talk about New Year's