The Archbishop of Canterbury, Justin Welby, has written about the personal impact of a trip to Auschwitz-Birkenau which he undertook this week.

Archbishop Welby visited the death camp along with a group of Anglican clergy on a theological trip. His reflections on the visit, which he published on his Facebook page, can be found in full below:

After visiting Auschwitz this week, here are some reflections on recognising and responding to evil:

This was my third visit to Auschwitz/Birkenau, and each time has been even more appalling. In early January the cold is penetrating, between 9 and 14 degrees below centigrade. We were fully equipped with snow boots, layers of clothing, hats, gloves, scarves... yet it worked through layer after layer until we were cold to the core. The prisoners wore the equivalent of pyjamas and clogs. We were out in that cold for five hours in the day. They would be out for 12 hours. We were fed. They were starved.

There are so many statistics about Auschwitz/Birkenau, but it defies description. Eighty-five per cent of prisoners died. Many in just days of arriving. Then there was the industrialized killing of the gas chambers. The vulnerable, the disabled, marginalised minorities, and above all the Jews: children, adults and the elderly, taken from a train to their deaths in as little as 30 minutes. Accounts were kept, profits were sought. No one can deny the reality of what happened. There is simply far, far, far too much evidence.

Our retreat at Auschwitz gathered the first cohort of the Learning Community (a group of Anglican clergy on a programme of in-service training) for three days of prayer and theological and scriptural reflection. We considered the issues of human evil: how we recognise it and how we respond.

Naturally it provoked so many questions:

Having seen this terrible place could we still speak of God? Could we still pray, and if so in what way?

Could we hear the tunes of evil in such a way that we recognise their modern variations?

Even if we recognised evil, how could we know we would have the courage to protest, to lament – and not be silent when horror threatened?

Here are three things that will stay with me:

First is the way that the perpetrators at Auschwitz tried to dehumanise their victims – in a way that actually cost the humanity of both. It worked to some extent. Prisoners killed others in order to live – and were then killed themselves. Others gave their lives, like St Maximilian Kolbe and St Edith Stein.

Second, these atrocities were committed by ordinary people. When one of the priests leading our retreat was asked who was to blame, he said: "People did it to people.”

Third, it was idolatrous and demonic. It was evil in the strict sense of human-created alternatives to the grace and providence of God. It reversed everything good with everything bad. During the retreat the Revd Dr Sam Wells gave three extraordinary reflections on this question.

Meanwhile the Very Revd Pete Wilcox reflected powerfully on Lamentations and Revelation – speaking of protest, hope and the call to endure.

I’ve come away with too much to write, and no words to write it. We must protest to the limit against evil: before it occurs, as it happens, and in its aftermath. But there is also a need for silent reflection – in which we honour the victims, mourn our capacity for evil, and learn to beware.