The Dutch bishops tried publicly opposing the roundup of Jews. The Nazis’ response was to accelerate their deportation program and to start killing converts from Judaism that they had previously spared.
https://www.ncregister.com/commentaries/the-bishops-who-defied-the-nazis
Should have done more. As FDR should have. Incredible what happened in WWII, the Japs too. Are we really going to let this happen again? Seems like it could happen.