In his Christmas message, the Right Reverend Justin Welby pointed to the example of the shepherds who celebrated the birth of Jesus in a manger despite being as "poor as you could be in those days".
"In tough times like these, it can sometimes be difficult to focus on the positive; talk of recession, news of redundancies and reports of worldwide conflict grinds us down. However, Christmas is a time for celebration, it always has been," he said.
"Christmas has been associated with partying not only because the early Church took over the early festival of Saturnalia, or the Winter Solstice, which was traditionally a time for general merrymaking, but also because what is being talked about is such good news. It is good news for people in bad situations."
However, he cautioned people not to get so carried away with festivities that "we forget who we are and why we live".
"At the heart of the greatest story ever told, the Christian story, the story that has shaped our civilisation, is the theme of self-giving and responsibility," he said.
Bishop Welby said he had found a capacity for joy and celebration that was "deeply challenging and quite overwhelming" among Christians suffering from severe persecution in northern Nigeria, where he has visited several times this year.
Despite economic uncertainties and global conflicts, the Archbishop-Designate said the sacrifice of others and the desire of people to share good things were causes for optimism this Christmas.
"Perhaps just going to see a neighbour, hurrying a bit less when someone wants to chat, we can all do that," he said.
"Perhaps we can give something to someone who has had a rough year, make space for them to have hope and joy."
Looking to the coming year, when he will become the 105th Archbishop of Canterbury, he said 2013 would be a "momentous" year for him.
"I will do everything in my power to ensure that I make a difference to the Church I love and the country we serve.
"The church gets lots of things wrong, it always has, always will, because it is full of human beings.
"But at its heart is the good news that when Jesus came God came to be with us, offer us hope and joy and purpose and love beyond all we can measure. That keeps me going."