"Los lugares más calientes del infierno están reservados para aquellos que en tiempos de gran crisis moral mantienen su neutralidad."

Simplified Meaning:

When something very wrong or unfair is happening and people choose to stay silent or do nothing, they're essentially allowing that bad thing to continue. This idea is conveyed in the quote, suggesting that doing nothing in tough times is a serious mistake, almost worse than doing the bad thing itself. Imagine a bullying situation at school: if you see someone being bullied and just stand by, not helping the victim or speaking up, you're indirectly supporting the bully. History also shows such examples; during the Holocaust, those who didn't act against the Nazis, even if they weren't actively supporting them, were helping the Nazis by not opposing them. In important moments, staying quiet or neutral means you're not fighting against the bad things happening. The advice here is to speak up and take action against wrongdoings, showing that you care about making things right.