Discriminatory policy towards practicing Catholics?

[Soldat7128]

My mother once told me a story about her older brother (who eventually died [as far as we know] on the Eastern Front); apparently he was dissatisfied with not being promoted from private to corporal, and once on leave from Russia (going back to Lower Saxony) he got off the train in Berlin and went to army headquarters to see his personnel file, in it under "Contraindications" [or some other such bureaucratic word] there was stamped a red 'K' for "Katholisch" (or 'GK' for Glauebige Katholisch) does anyone know if this was an actual practice?