Some points I would make if tattooing came up in debate:
- The SS had blood type tattoos, as mentioned above.
- The forced tattooing of prisoners was practiced in the 18th and 19th centuries on British convicts. Also in ancient Greece, Rome, China, and Japan. (See
Wikipedia.)
- Tattooing proves killing was not the objective.
- Tattooing seems to have been implemented only in Auschwitz and only for some of the inmates, so its relevance to the Holocaust debate is limited.
- Resistance against the Nazis is something many Jews boasted proudly about after the war. One means or means to an end of resistance, in and outside the camps, was to change one's identity. For example, a Jewish organization called Zegota estimated that they printed 50,000 sets of false identity documents (discussed
here). Tattooing ID numbers likely arose as a way to combat these acts of resistance (evidenced in part
here).