The King's Christmas message has emphasised the importance of "universal" values shared between major religions, at a time of "increasingly tragic conflict around the world".
Against a backdrop of conflicts in Israel, Gaza and Ukraine, he pointed to Jesus's words: "Do to others as you would have them do to you."
King Charles also talked of protecting the planet as being a spiritual duty.
And he praised the efforts of volunteers helping those in need.
The King's second Christmas broadcast, recorded in Buckingham Palace, wove together some of his most personal causes - building bridges between faiths, protecting the environment and caring for the most vulnerable.
He has long campaigned for supporting links between different religious communities, at home and abroad, and a major theme of this year's message is how much the major religions have in common, despite the violence raging in the Middle East and elsewhere.
The King spoke of the universal values of respecting others in the "Abrahamic family of religions", which includes Judaism, Islam and Christianity.
"I pray that we can also do all in our power to protect each other," said the King, urging greater tolerance for people to "imagine ourselves in the shoes of our neighbours, and to seek their good as we would our own".
If the replantable Christmas tree beside the King sent its own seasonal message, there was a strong environmental theme to the speech.
"Honouring the whole of creation" is a "belief shared by all religions", said the King, who gave the key address at the recent COP28 climate change summit in Dubai.
"To care for this creation is a responsibility owned by people of all faiths and of none. We care for the Earth for the sake of our children's children," he said, linking spirituality to environmentalism.
The King referenced the role of the "close to nature" shepherds in the story of Jesus's birth - and the broadcast includes the carol 'While Shepherds Watched Their Flocks' sung by a community choir from Bexley, a group designed to widen access to music.
Such speeches from the King have to find the balance between addressing major themes of the day, while at the same time avoiding accusations of treading into politics.
And his Christmas message spoke of protecting those in need of help, whether strangers or one's own family.
He marked his 75th birthday by launching the Coronation Food Project to support surplus food being shared to food banks and to reduce food waste, with images of this scheme shown during the recorded message.
"This care and compassion we show to others is one of the themes of the Christmas story, especially when Mary and Joseph were offered shelter in their hour of need by strangers, as they waited for Jesus to be born," said the King.
The King praised the volunteers and those who cared for others as the "essential backbone of our society".
The annual speech was overlaid by pictures of key moments of the year, such as the Coronation and overseas state visits.
It also included other members now at the centre of the the Royal Family - including the Prince and Princess of Wales, the Duke and Duchess of Edinburgh and the Princess Royal.
"So on this Christmas Day, my heart and my thanks go to all who are serving one another; all who are caring for our common home; and all who see and seek the good of others, not least the friend we do not yet know. In this way, we bring out the best in ourselves," said the King, bringing together his themes.
