The Queen's annual Christmas broadcast message encourages viewers and listeners "to be thankful for the people who bring love and happiness into our own lives and to look for ways of spreading that love to others," despite the tragic events the world faced in 2015.
"It is true that the world has had to confront moments of darkness this year," the Queen said, although she did not give any specifics. "But the Gospel of John contains a verse of great hope often read at Christmas carol services: 'The light shines in the darkness. And the darkness has not overcome it.'"
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The annual message is pre-recorded each year and broadcast in many parts of the world.
This year, she used the Christmas tree as a theme throughout her speech.
"At this time of year, few sights evoke more feelings of cheer and goodwill than the twinkling lights of a Christmas tree," she began.
"Gathering around the tree gives us a chance to think about the year ahead," she continued. "It also allows us to reflect on the year that has passed, as we think of those who are far away or no longer with us."
But, she said, it is also a time to "remember all that we have to be thankful for."
'Joys of living a long life'
In particular, the Queen recalled last summer's 70th anniversary of the end of the Second World War as an occasion for gratitude.
"On VJ-Day, we honoured the remaining veterans of that terrible conflict ... as well as remembering the thousands who never returned."
The Queen said that her great-great-grandparents, Queen Victoria and Prince Albert, helped inspire the custom of decorating a tree for Christmas, noting that they chose to place an angel at the top to commemorate Christ's birth.
"Despite being displaced and persecuted throughout his short life, Christ's unchanging message was not one of revenge or violence, but simply that we should love one another," the Queen said. "Although it is not an easy message to follow, we shouldn't be discouraged."
The Queen also used the Christmas tree theme in reference to her youngest great-grandchild, Princess Charlotte, who was born in May.
"One of the joys of living a long life is watching one's children, then grandchildren, then great-grandchildren help decorate the Christmas tree," the 89-year-old monarch said. "And this year my family has a new member to join in the fun."
Royal Family takes in church service
For the Queen and the other members of the Royal Family, Christmas Day started with a church service amid the sprinkles of rain.
Prince Charles and his wife Camilla were among the royals attending the service at St. Mary Magdalene Church on the Sandringham estate as some 1,000 well-wishers marked the festivities, which included the National Anthem and several hymns.
Prince William and his wife, Kate, came as well, but they left George, 2, and seven-month-old Charlotte at home. Kate wore a green coat and hat and chatted with brother-in-law Prince Harry.
The Queen, her husband Prince Philip and senior members of the Royal Family plan to spend most of the day at her sprawling Sandringham estate in Norfolk, 175 kilometres north of London. There is usually a gala Christmas lunch for the royals after church, followed by a walk outside.