asked by Frederic, Canada
Russia has been Christian since 980 A.D. (for over 1000 years) and the Russian Orthodox Church still follows the old Julian Calendar. The Julian calendar is currently 13 days behind the Gregorian Calendar which is used by the majority of the countries in the world including the Russian State. According to tradition, all Russian Orthodox believers celebrate their Christmas on January 7th of the following year.
It was not always like this. Until 1917 the Russian State celebrated Christmas as lavishly as the rest of Europe but with an official delay of 13 days. So kids received their Christmas presents on that day. This holiday opened seasonal festivities of Russian Imperial court and nobility, which continued until the Lent before Easter.
When at the end of 1917 the Bolshevik government decided to adopt the Gregorian calendar, the Russian Orthodox church decided not to follow the rules set by the increasingly hostile civil authorities. Part of the reason was to protest against the Bolsheviks and their interference in church affairs. Another reason, probably, was to preserve the older/ Orthodox (read "unchangeable") rules, and ways in which the previous generations of Russian Christians were praying, celebrating, etc.
So the new Soviet State also marked its territory by forbidding all possible reminders of "the Old times". That naturally banned Christmas trees and Christmas day became a working day. But still parents didn't want to deny their kids the pleasure of decorating a Christmas tree on long winter evenings. My grandmother remembers that even though the people were afraid of repressions they covered windows with blankets when they put a small tree in.
It was like this until 1935 when one of the party leaders addressed the Communist Congress with a clever note mentioning that "the most civilized State offering everyone an equal chance can't deprive its happy children of presents and the New Year celebration under the wise control of the Communist Party". That argument was unbeatable and here once more - tradition won. Now New Year became a Soviet version of an old Christmas celebration. Presents, Santa, and trees were adopted by the Soviet Union. Lenin had been dead for a long time, but every school had a right to a nice picture of him visiting children for the New Year.
It was only in 1938 when the Communist Party officially organized a Christmas/New Year tree inside the Kremlin and every small visitor had a right to a small present offered from Grandpa Frost (the Soviet version of Santa Clause).
The end of the war brought another calendar change, though. Now, the 1st of January officially became a day off.
People were allowed to have a celebration and all Soviet newspapers showed happy families united for New Year's Eve.
As time went by and the regime softened, Soviet traditions included great festivities for the New Year with an obligatory Grandpa Frost's visit often accompanied by his granddaughter Snegurochka (Snow Maiden).
Like his Western counterpart Santa, Russian DED MOROZ (Grandpa Frost) travels in a sled (albeit with a Troika) and there are no unreachable places for this omnipresent old man. He prefers the daytime for visits, though ))))
For the not-so-religious part of the Russian society, Christmas time is just a long holiday season.