On 25 December each year, over 2 billion people (over a third of the world's population) will celebrate the birth of Christ. The bible didn't give any specific details on the exact date or year that Christ was born and many have speculated when the actual date was. By the fourth century, the early church had plumped for 6 January but as the religion gained popularity across the Roman Empire, they realised that Christmas Day was be competing with the existing Roman festival of 'Sol Invictus'. As is the case with many of our holidays, the Christians decided the best course of action was to switch Christmas day to 25 December, so that both holidays would be celebrated on the same day and eventually Christmas Day would outlast Sol Invictus. To keep 6 January as a holy date, Epiphany was then celebrated on 6 January.
Observed in: Armenia, Lebanon (by Armenian Lebanese)
In regions outside the influence of the Roman Empire, such as Armenia, there was no competing holiday such as Sol Invictus. This meant that the Christian church had no reason to move the date of Christmas, so the original date of 6 January stayed as it was.
Observed in: Georgia, Kazakhstan, Russia, Serbia, Ukraine
The Orthodox Church recognises 7 January as the day that Jesus was born. The different date from the western tradition of 25 December is twofold. Firstly, in 1582, Pope Gregory XIII, ruled that the Catholic Church should follow a new calendar – called the Gregorian calendar rather than the Julian calendar which had been established by Julius Caesar in 46BC. This meant the dates differed by 10 days with Gregorian Christmas on 4 January. Secondly, due to the way that leap years differ between the two calendars, Orthodox Christmas has moved forward by another 3 days since 1582 and is now on 7 January. By 2100 AD, Orthodox Christmas will be celebrated on 8 January.
In the post soviet era, Orthodox Christmas has become a new holiday in some countries with an Orthodox community. To encourage adoption, it often forms the end part of an extended winter holiday that starts with New Years Day.
Observed in: Egypt, Ethiopia, Eritrea (by Coptic community)
The Coptic calendar, also called the Alexandrian calendar, is used by the Coptic Orthodox Church. This calendar is based on the ancient Egyptian calendar and similar to the Julian Calendar used by the Orthodox Church.
The following is a list of countries that don't observe a public holiday for Christmas: Afghanistan, Algeria, Azerbaijan, Bahrain, Bhutan, Cambodia, China, Comoros, Djibouti, Iran, Israel, Jordan, Kazakhstan, Kuwait, Laos, Libya, Mauritania, Mongolia, North Korea, Oman, Qatar, Saudi Arabia, Somalia, Tajikistan, Tunisia, Turkmenistan, United Arab Emirates, Uzbekistan, Vietnam and Yemen.