I wasn’t trying to attest to the core reasoning for war. Fact is that much of the atrocities weren’t uncovered until well into the war. My point is that atrocities are out in the open with ISIS, but everyone continues to go about their day as if nothing is wrong.
I understand your point. But Americans had knowledge of Japanese atrocities in China before Pearl Harbor, but there was no call for war against Japan. It wasn’t considered to be “our problem”. Even when it became our problem with the sinking of Panay, there were no calls for war.
Most Americans didn’t admire Hitler and we didn’t agree with his treatment of the Jews, but again, it wasn’t “our problem”. We turned away a boatload of Jewish refuges (SS St. Louis) trying to escape Germany.
The French and Brits drew a “red line” at Poland. When that red line got crossed, they did something about it (unlike red lines drawn by Nobel Prize winners). As a result, the Brits lost their empire, and the French their national self-respect. And in the end, Hitler pretty much achieved his goal—a Europe free of Jews.