Hemingway, Humanism & Post-Christianity

I am reading Hemingway's For Whom the Bell Tolls, which he wrote as a thinly dissimulated narrative of his time fighting for the "Republic" during the Spanish Civil War. One exchange, between American guerrilla bomber Robert Jordan and his elderly guide Anselmo, perfectly captures the urge of 20th century secular humanists to have Christian values without Christianity:

"You have killed?" Robert Jordan asked in the intimacy of the dark and of their day together.
"Yes. Several times. But not with pleasure. To me it is a sin to kill a man. Even Fascists whom we must kill. To me there is a great difference between the bear and the man and I do not believe the wizardry of the gypsies about the brotherhood with animals. No. I am against the killing of men."
"Yet you have killed."
"Yes. And will again. But if I live later, I will try to live in such a way, doing no harm to any one, that it will be forgiven."
"By whom?"
"Who knows? Since we do not have God here any more, neither His Son nor the Holy Ghost, who forgives? I do not know."
"You do not have God any more?"
"No. Man. Certainly not. If there were God, never would He have permitted what I have seen with my eyes. Let them have God."
"They claim Him."
"Clearly I miss Him, having been brought up in religion. But now a man must be responsible to himself."
"Then it is thyself who will forgive thee for killing."
"I believe so," Anselmo said. "Since you put it clearly in that way I believe tat must be it. But with or without God, I think it is a sin to kill. To take the life of another is to me very grave...."

I think I would have fought for Franco in spite! Hemingway at least invented the Montgomery.