David Cameron has stressed his commitment to "Christian values" as he delivered his seasonal message to the country.
The Prime Minister said "giving, sharing and taking care of others" at home and around the world was something Britain could be proud of.
Meanwhile, Labour leader Ed Miliband issued a more politically partisan Christmas missive, urging voters to choose "generosity and inclusion" in the looming election battle next year.
Mr Cameron - the only one of the three main party leaders to describe himself as Christian - praised the work of the military, aid workers and medical volunteers abroad.
"Among the joyous celebrations we will reflect on those very Christian values of giving, sharing and taking care of others," the Tory leader said.
"This Christmas I think we can be very proud as a country at how we honour these values through helping those in need at home and around the world.
"On Christmas Day thousands of men and women in our armed forces will be far from home protecting people and entire communities from the threat of terrorism and disease.
"NHS doctors, nurses and other British volunteers will be in Ebola-affected countries, working selflessly to help stop this terrible disease from spreading further.
"And British aid workers will be helping citizens to rebuild countries and communities afflicted by conflict and poverty.
"Here at home thousands of police and fire officers, paramedics and other emergency service personnel will be working hard to keep the public safe and well.
"Across the country volunteers and workers from charities and other organisations will drop in on the vulnerable and elderly so they are not isolated this Christmas.
"And thousands of churches - whether in the smallest village or biggest city - will hold open their doors and welcome people of faith and none to give thanks and celebrate together.
"So this Christmas, as we celebrate the birth of Christ with friends, families and neighbours, let us think about those in need at home and overseas, and of those extraordinary professionals and volunteers who help them."
Earlier this year Mr Cameron came under fire for stoking "alienation and division" when he insisted that Britain is a "Christian country".
The message from Mr Miliband - who is an atheist - recalled the famous truce observed by soldiers in the First World War trenches.
"One hundred years ago soldiers on the Western Front stopped their hostilities to cross no man's land, to shake hands and - famously - to play football. In the midst of a tragic conflict the generosity, hope and sense of human solidarity that is characteristic of the Christian faith and culture came to the fore. What an extraordinary and unexpected event," he said.
"We need the same sense of compassion in the face of the suffering and hatred that afflicts parts of our world. And especially in the Middle East, the cradle of Christianity. Let us remember those caught up in fighting and in fear of their lives.
"I am proud that the Labour movement has such deep roots in the Christian tradition of social activism and solidarity in the United Kingdom. This Christmas, I want to pay tribute to all who spend time, effort and skill in serving the needs of their fellow citizens in a voluntary and professional capacity.
"Our country faces a choice next year. Let's choose generosity and inclusion. I hope you have a very merry Christmas and a peaceful New Year."
Liberal Democrat leader Nick Clegg also based his message on the Christmas truce.
In a possibly unintentional reminder of the current festive break in the brutal political battle, the Deputy Prime Minister said it had offered soldiers on both sides a "moment's respite" from the violent conflict in which they were engaged.
"This Christmas and beyond, we can each do our bit to help secure the fairer, more peaceful world that the soldiers in 1914 longed for and our children deserve: reaching out to those people - wherever they may be - who feel isolated, who are caught up in conflict or who need our help," he said.
Recorded at a west London primary school and posted on the DPM's office website, Mr Clegg's video included a thank-you to the armed forces personnel, emergency services and carers working through the festive period to keep others safe and well.
Mr Clegg, who is an atheist, said that the "heart" of the Christmas festivities is "the birth of Jesus Christ, a time of joy and celebration for Christians around the world".
The Christian values of love, charity and hope expressed through the story were "universal, speaking to and uniting people of all faiths and none", he said.