11 days were removed in 1752 (in the British world). The Julian calendar has the last year of every century as a leap year, the Gregorian calendar fixes that by making the last year of a century a leap year only if it's divisible by 400. The difference between Julian and Gregorian has increased to 13 because of 1800 and 1900...
Hence Julian 25/12/13 is Gregorian 7/1/14. Since the world uses Gregorian, Julian (Orthodox) Christmas occurs on 7 January 2014
"Its +13 days"
Still trying to figure out if that is 13 ahead or behind.
Suggested bounty - A VOX sentence parser, something that breaks down and translates VOX's posts into intelligible English.
BTW - Happy Birthday young man.