Snake Featherston
Banned
Churchill did not want the French civilian population to get into a bloodly war with the Germans there at least by 1942-44 he didn't. Czechoslovakia or Eastern Europe were a different story. But, if the French resistance got too violent their cities would have been wiped out as the German Army left instead of Hitler repeately asking is Paris burning while his orders to burn the city end up in the waste basket. Lets just say French post war relations with West Germany would have been much much worse then OTL for decades after WW2 ended. It also would not have speed up the end of the war much at all.
And that in turn only helps the USSR in the Cold War in the long term by making it unlikely most of Europe would accept German re-armament and making an effective NATO very, very difficult.
Why are we limiting ourselves to only French resistance?
As for specific mindset -- what situations would cause the resistance fighters to adopt such a mindset? And don't start with the "it is impossible for Christian Europeans to think such things" - I already discussed this with Heratic and gave examples from Bible and folklore.
Because the Soviets were in a literal apocalyptic war IOTL and never used it and it's almost impossible to make Nazi atrocities there worse than OTL in the USSR. Short of them capturing Leningrad and doing something like a Rape of Nanking, and that's not going to push the Soviets and their proxies into suicide attacks.