Admittedly, this is an interpretation of Barth, but I would be interested in hearing from others if they have other quotes on this subject.
The Protestant theologian Karl Barth is purported to have been asked such a question. Bear in mind that Barth was one of the greatest Christian theologians who defied Hitler, yet when he was asked such a question, he would cite the passage from Romans 5:8-9 that reads, But God proves his love for us in that while we were still sinners Christ died for us. How much more then, since we are now justified by his blood, will we be saved through him from the wrath. Only such unparalleled mercy and forgiveness, such unstinting gladness could have prompted the Führer’s genuine repentance. To accuse him, though justly, of his dreadful sins would have prompted Hitler’s self-righteous defense, his angry justification of his ‘necessary’ deeds.”