While Russia's Orthodox Christians celebrate Christmas Eve according to the Julian calendar on Jan. 6, the country's many other Christian denominations celebrate it on Dec. 24 — together with much of the Western world.
To celebrate the holiday, thousands of Catholics, Protestants, Lutherans and adherents of other Christian denominations attended services in churches across Russia on Dec. 24.
Here's a look at the celebrations through Instagram:
In Moscow, big Christmas services were held at churches including the Cathedral of the Immaculate Conception of the Holy Virgin Mary, the Evangelical-Lutheran Cathedral of Saints Peter and Paul and the Church of St. Louis of the French.
"It's so crowded in the church at midnight. But there's always a beautiful mass, choir, organ and Christmas carols," a parishioner wrote.
Online videos showed crowds of people walking to church bells and music.
Russia has had large Catholic, Protestant and Lutheran communities since the 18th century.
"Christmas Eve on Dec. 24 is considered a fasting day. There is a tradition of Christmas dinners, Christmas Eve celebrations at the family table or among parishioners. There is also a tradition of breaking special Christmas bread," Fr. Igor Kovalevsky, a Catholic priest in Moscow, told the state-run TASS news agency.
Christmas midnight mass was also served in St. Petersburg's Church of St. Catherine on Nevsky Prospekt, the city's main street.
Services were held in many different languages for the different expat communities.
Languages included Russian, English, Polish and French.
Here is the Roman Catholic parish of St. Anna in Yekaterinburg, decorated with a Christmas tree and the perfect place to find a festive mood.
Here is a video of beautiful music being played at a church in Kaliningrad, Russia's westernmost region.