cardinal sin

noun

1. theol any of the seven deadly sins
2. informal.
   an unforgivable error or misjudgment

   lack of impartiality is considered a cardinal sin in broadcasting circles

Example Sentences

Attributing consciousness to animals based on their responses was seen as a cardinal sin.

From BBC

Johnson may have risked losing his speakership because he reached out to Democrats—a cardinal sin in the eyes of extremist House Republicans—in order to pass the package.

From Slate

They started with an epic battle for the speaker's office that ended even before the year was up with the dramatic defenestration of that same speaker for committing the cardinal sin of compromising with the Democratic Senate and White House to keep the government running.

From Salon

The residents’ cardinal sin is placing all the responsibility on a single man, eager to wash their hands of any guilt.

From Los Angeles Times

Allowing high inflation to become embedded in the economy is central banking's cardinal sin, and Fed officials would still rather make the mistake of going too far to be sure inflation is controlled than stop short and risk its rebound, said Antulio Bomfim, head of global macro for the global fixed income team at Northern Trust Asset Management and a former special adviser to the Fed's board of governors.

From Reuters