The Archbishop of Canterbury has urged the UK government to be generous in its response to the refugee crisis, saying that the UK should demonstrate a "shared humanity".

Writing in the Big Issue this month, Archbishop Justin Welby praised Britain for its "long and wonderful history of offering shelter to migrants". David Cameron's government has promised to resettle 20,000 Syrians in the UK by 2020, and 1,000 of them by the end of this year.

"The scale of the problem we are facing as a global human family is astonishing," Welby said. "The families coming to us from Syria will be among the most vulnerable and traumatised people affected by this crisis.

"This is a moment for all of us in the UK to demonstrate our shared humanity with those for whom daily life has become dominated by fear, violence and suffering," he added.

Welby admitted there are "doubts and fears" among the British population as refugees begin to arrive. "Do we have room? Do we have the money? Will our communities fragment? Are we putting ourselves at risk? These questions are all valid and vital – they must be asked, and answered as best we can.

"They also point to a deeper and perhaps more urgent question, however: as a country, do we have the emotional and spiritual capacity to welcome those who need our help in the months and years ahead?

"I pray that we do have that capacity – the same capacity we've had for centuries when people have turned to us in crisis.

"It's always been controversial at the time. It's always been seen as too difficult. Yet each time we have risen to the challenge and benefited from the gifts those coming to us bring."

The Archbishop also made a nod to accusations that refugees come to the UK not because they are fleeing war or persecution, but instead merely in search of a more comfortable life.

"My experience, having worked in this area for many years, is that you very seldom meet people who want to be refugees," he said.

"It is a desperate, awful, terrible existence. You leave home when the alternative is death."

It is not the first time Welby has spoken out about the refugee crisis. In September, he released a statement calling on Christians to "break down barriers, to welcome the stranger and love them as ourselves (Leviticus 19:34), and to seek the peace and justice of our God, in our world, today."

"This is a hugely complex and wicked crisis that underlines our human frailty and the fragility of our political systems. My heart is broken by the images and stories of men, women and children who have risked their lives to escape conflict, violence and persecution," he said.

"There are no easy answers and my prayers are with those who find themselves fleeing persecution, as well as those who are struggling under immense pressure to develop an effective and equitable response. Now, perhaps more than ever in post-war Europe, we need to commit to joint action across Europe, acknowledging our common responsibility and our common humanity."

Welby announced earlier this year that he would be offering an empty four-bed cottage at Lambeth Palace to a refugee family from Syria.

A spokesman said: "As the archbishop has said, Jesus was a refugee, and there are refugees here who are desperate for sanctuary from war-torn places and the archbishop is completely torn about their situation and wants to make a difference."