Over Rosh Hashanah, I used the Koren machzor. Of the many outstanding commentaries by the late Rabbi Jonathan Sacks, this stood out:

The Rabbi of Klausenberg, Rabbi Yekutiel Yehuda Halberstam, who survived Auschwitz and lost his wife and eleven children in the Holocaust, once said: “The biggest miracle is that we, the survivors of the Holocaust, after all that we witnessed and lived through, still believe and have faith in the Almighty G-d, may His name be blessed. This, my friends, is the miracle of miracles, the greatest miracle ever to have taken place.” As he said these words, he wept. But still he believed.