The King has used his first Christmas Day speech as sovereign to pay tribute to his mother, the late Queen's Christian faith.
In the first televised Christmas address by a king, King Charles thanked the nation for their "touching" letters, cards and messages after the death of Queen Elizabeth II earlier this year.
Speaking about bereavement at Christmas, he said, "Christmas is a particularly poignant time for all of us who have lost loved ones.
"We feel their absence at every familiar turn of the season and remember them in each cherished tradition.
"In the much-loved carol O Little Town Of Bethlehem we sing of how 'in thy dark streets shineth the everlasting light'.
"My mother's belief in the power of that light was an essential part of her faith in God, but also her faith in people and it is one which I share with my whole heart.
"It is a belief in the extraordinary ability of each person to touch, with goodness and compassion, the lives of others, and to shine a light in the world around them.
"This is the essence of our community and the very foundation of our society."
The King's Christmas Day speech was recorded by the King in St George's Chapel, Windsor.
He thanked the "selfless dedication" of the armed forces and emergency services, as well as charities and the "wonderfully kind people" giving food and donations to help people in need in their communities.
He paid particular tribute to places of worship serving their communities.
"Our churches, synagogues, mosques, temples and gurdwaras, have once again united in feeding the hungry, providing love and support throughout the year," he continued.
"Such heartfelt solidarity is the most inspiring expression of loving our neighbour as our self."
The King also spoke about fulfilling a "life-long wish" to visit Bethlehem and the Church of the Nativity, traditionally revered by Christians as the site of the birthplace of Christ.
"It meant more to me than I can possibly express to stand on that spot where, as the Bible tells us, 'The light that has come into the world' was born," said the King.
"While Christmas is, of course, a Christian celebration, the power of light overcoming darkness is celebrated across the boundaries of faith and belief.
"So, whatever faith you have, or whether you have none, it is in this life-giving light, and with the true humility that lies in our service to others, that I believe we can find hope for the future."
He concluded his address, "Let us therefore celebrate it together, and cherish it always.
"With all my heart, I wish each of you a Christmas of peace, happiness and everlasting light."
