The key word, in fact, of our priestly apostolate in the camps had to be the word 'witness'. It wasn't so much a matter of preaching God and talking religion to the men around you as it was a matter of living the faith that you yourself professed.
It was not always a matter of preaching God and religion. It was enough at times to simply respect each of your fellow men in the camp, to do good to each no matter what he himself did or said, no matter how he acted toward you ... There was little call to preach about sin or damnation or hellfire to men who experience daily the hell of loneliness and separation and anxiety. A great deal of tolerance and a great deal of understanding were required of a priest if he wished to be effective among these unfortunate and almost degraded human beings. Common sense and intuition, a feeling for the finger of God's grace behind a question or a conversation or an encounter, was much more necessary than textbook answers in theology." - The Priesthood, He Leadeth Me, Walter Ciszek, S.J.