You said that the first reason was a lie. I assumed you meant that all German soldiers were concerned with what race/religion the enemy was.
I didn't say all, what I mean is that a great deal of German soldiers were vehemently tribal, or were, at the very least, indoctrinated by national socialist tribal policy. For example, for the official order
Treatment of offences committed by members of the military, two things are mentioned
For cruelties committed by members of the military and their retinue against enemy civilians, there is no [threat of] prosecution; the same holds true if the offense is simultaneously a military crime or offense.
that is literally a carte-blanche to do whatever you want to the civilian population, no prosecution for war-crimes, no court-martial
In the assessment of such acts, in each proceeding, it must be taken into consideration the collapse in 1918, the later period of suffering of the German nation and the battle against National Socialism with countless sacrifices of blood were crucial to reduce Bolshevism’s influence and that no German has forgotten this.
oh hey, look, in this military order to the wehrmact there is a definite reference to losing the first world war, and a political slant was introduced.
additional, general field marshall von reichenau order his troops (the entire sixth army) that
...The most important objective of this campaign against the Jewish-Bolshevik system is the complete destruction of its sources of power and the extermination of the Asiatic influence in European civilization. ... In this eastern theatre, the soldier is not only a man fighting in accordance with the rules of the art of war, but also the ruthless standard bearer of a national conception. ... For this reason the soldier must learn fully to appreciate the necessity for the severe but just retribution that must be meted out to the subhuman species of Jewry. ...
that seems very... tribal and anti-semitic, especially coming from a man who was practically second to Riddler in the chain of command at the time. remember, this was a very popular general who commanded the respect of his men. if his men respected and emulated him, perhaps they might've picked up a little of what he thought.
citations:
http://users.clas.ufl.edu/ggiles/barbaros.htmlhttp://en.wikipedia.org/wiki/Severity_Order