Archbishop Welby said Christian communities in the Middle East were being "attacked and massacred" in his first Christmas sermon:
Today, singing of Bethlehem, we see injustices in Palestine and Israel, where land is taken or rockets are fired, and the innocent suffer.
We see injustice in the ever more seriously threatened Christian communities of the Middle East.
They are attacked and massacred, driven into exile from a region in which their presence has always been essential.
The Archbishop of Canterbury has used his first Christmas Day sermon to highlight the "injustices" facing Britain's poor and victims of conflicts around the world.
The Most Rev Justin Welby called on Christians to "challenge the causes of poverty" despite signs of an economic recovery in the UK, as he addressed the congregation at Canterbury Cathedral.
The Archbishop of Canterbury has posted a Christmas video message on Instagram.
The Most Rev Justin Welby appears in the short clip on the photo-sharing website as part of the Church of England's social media campaign called Christmasmeans.
Mr Welby, who has more than 48,000 followers on Twitter, joined Instagram in October in his drive to spread the Christian message to the app's 150 million users worldwide.
In his Christmas message, the Archbishop says: "Christmas means that, through Jesus, God shows unconditionally that he loves us. I pray that he gives you a very blessed Christmas."
The video, posted on Lambeth Palace's Instagram account, is also being tweeted by the Archbishop and through the Lambeth Palace Twitter page, lambethpalace.
The Archbishop of Canterbury, the Most Rev Justin Welby, said:
The death of President Nelson Mandela was announced in memorable words by President Zuma.
South Africa has lost its greatest citizen and its father.
Nelson Mandela, fighting to the end, is freed to be with his God in joy and reward for his great service and sacrifice.
We pray for his family, for his friends and for his country.
We are challenged to show the same degree of humanity, of courage and of generosity.
Archbishop of Canterbury Justin Welby's statement that a spending culture at Christmas is making people "miserable" has sparked public reaction on Facebook.
Writing on the social networking site, Laurie Turner said: "I can't see the point of getting into debt just for one day. If you haven't the money, don't buy it."
Jackie Perry blamed advertising: "What do you expect when children and adults alike are bombarded with media hype and having Christmas adverts rammed down their throats from October."
But Nicola Bulloc said: "I am on a low wage but I always manage to buy all the presents and bits without getting in debt."
To add your voice and let us know your views, comment on the ITV News Facebook page.
The Archbishop of Canterbury has told ITV that he thinks people spending big on Christmas presents are risking their relationships.Read the full story ›
The Duke and Duchess of Cambridge's son Prince George will be christened later in front of close family and friends of his parents.
The three-month-old baby, who will one day be king, will be baptised by the Archbishop of Canterbury, the Most Rev Justin Welby, in the little known Chapel Royal at St James's Palace this afternoon.
The Queen and Duke of Edinburgh are expected to be at the ceremony along with the Prince of Wales, who has become a grandfather for the first time, the Duchess of Cornwall and Prince Harry.
Kate's family - parents Carole and Michael Middleton and siblings Pippa and James - are thought to be invited, along with the godparents who, like the guests, have not been publicly named.
The Archbishop of Canterbury said he hoped that people would not view baptism as only for a future king or "special people."
Of course, the great good news is that God doesn't care who we are. It's for adults and children. And there may be people wondering: 'I wonder if that's at all possible for me or for my family or for my child or for all of us together?' And the answer is it's not just possible, it's extremely easy.
God's love is offered without qualification, without price, without cost, to all people in all circumstances always.
The Archbishop of Canterbury said the baby son of the Duke and Duchess of Cambridge would be joining two billion people around the world in the "family of the church" when he baptises him tomorrow at St James's Palace in central London.
The father-of-five, and former oil executive said the ceremony would mark the next "hugely important" moment in Prince George's life following his birth on July 22.
Mr Welby, who has already spoken of the "great privilege and honour" of baptising George, said he was sure that the Duke and Duchess of Cambridge would have received so much advice that they could "probably fill a house with it."
He said: "My message to them would be - what a treat, what an amazing gift, what wonderful times that you will have.
"There'll be great times and tough times - there always are with children.
"Through christening you're bringing God into the middle of it all, and I know that when he's in the middle of it all somehow it's held in his hands, and that's extraordinary."
The Archbishop of Canterbury has warned MPs not to rush their decision on whether to vote for military intervention in the Syria conflict.
Ahead of tomorrow's early return to Parliament, the Most Rev Justin Welby said he feared the possible consequences of intervention, saying they were "beyond description and horrible".
He told the Daily Telegraph: "I have had a lot of conversations with people in the region.
"I think the overwhelming sense is of a really moving and terrible sense of fear about what might come out of, what might be happening in the next few weeks - not predicated on people doing one thing or people doing another, just a sense that this a terribly, terribly dangerous time."
However, the Archbishop acknowledged that the Government was better informed than he was, making clear that he had no sense that politicians were "slavering" to "unleash the dogs of war".