The New Year?

Today is the first day of 2007 AD or to be areligious - 2007 CE (Common Era) as AD stands for the latin word Anno Domini - the year of our lord or as the Oxford Dictionary pointed out AD refers to 'of the Christian Era'. So, why were you singing the old Scottish song Auld Lang Syne (written by poet Robert Burns and published in 1796) to celebrate the 'new year' last night?In the middle ages, even