I read Man's Search for Meaning by Viktor Frankl around half a year ago or so, and something I've been left wondering is why the Nazi/SS guards refer to men who no longer are fit to work due to illness in the slave camps as "Moslems". When I look this word up, all I find is that it's an old word for "Muslim", but the people in the camps were Jews, not Muslims, so I don't understand why they would refer to them like that. Is there any known reason why they would refer to these people that way?
This usage is not confined to just Frankl. For example, Jean Amery in his memoir At the Mind's Limits: Contemplations by a Survivor on Auschwitz and its Realities noted that this was the term used generally in the camp:
The so-called Muselmann (i.e. Moslem/Muslim), as the camp language termed the prisoner who was giving up and was given up by his comrades, no longer had room in his consciousness for the contrasts good or bad, noble or base, intellectual or unintellectual. He was a staggering corpse, a bundle of physical functions in its last convulsions.
and similarly Primo Levi, another survivor of the camp, confirms this usage (Survival in Auschwitz and the Reawakening: Two Memoirs):
With the word 'Muselmann', the elders in the camp designated, for reasons unknown to me, the weak, the infirm, those who were doomed to be singled out.
but does not speculate on the reason for it.
Various theories have been advanced to explain why this term was used, and they mainly hinge on the perceived resemblance of these prisoners' behavior to that of Muslims. The Encyclopedia Judiaca gives the explanation:
MUSELMANN (German for Muslim), death camp slang word for prisoners on the edge of death who have surrendered to their fate, i.e., showing the symptoms of the last stages of hunger, disease, mental indifference and physical exhaustion. This term was mostly used at Auschwitz. It seems to have originated from the typical deportment of the sufferers, e.g., to squat with their legs tucked in an "Oriental" fashion, their faces masklike in stiffness.
so that the prisoners were squatting in an "Oriental fashion", while Wolfgang Sofsky (The Order of Terror: The Concentration Camp) equates the swaying of the weakened prisoners with Islamic prayer rituals.
Another explanation, drawn from the perception of Islam, is given by Giorgio Agamben (Remnants of Auschwitz: The Witness and the Archive), who wrote:
The most likely explanation of the term can be found in the literal meaning of the Arabic word muslim: the one who submits unconditionally to the will of God. It is this meaning that lies at the origins of the legends concerning Islam’s supposed fatalism...
I have to say this explanation does not sound terribly convincing to me. I find it unlikely the concentration camp guards would coin a nickname based on the literal meaning of the term muslim (submission).
Finally, it is worth noting that in his book, Kingdom of Auschwitz, Otto Friedrich gives the explanation:
Auschwitz prisoners easily recognized these marks of coming death, and with the stinging acerbity of the death camps, they likened the numbed victims to the starving beggars of India and named them Musselmanner, or Moslems.