The phrase "a pernicious idea" is correct and usable in written English.
It can be used to describe an idea that is harmful or destructive, often in a subtle or insidious way.
Example: "The notion that success is solely determined by wealth is a pernicious idea that can lead to societal inequality."
Alternatives: "a harmful notion" or "a toxic belief".
The paradox of thrift has been a pernicious idea.
Some applications of mammalian cloning technologies may be beneficial, but human cloning itself is a pernicious idea.
It is a pernicious idea precisely because once you believe in it, you find yourself forced to match all contemporary activity against it.
We have been at war continuously these last 10 years against a pernicious idea as much as against a shadowy enemy.
The New American cited Peter Sprigg of the Familly Research Council telling the Christian Post that early-childhood sex education "is part of the legacy of Alfred Kinsey, and the belief that 'children are sexual from birth.' This is a false and pernicious idea that introduces words, thoughts, and concepts to children long before it is developmentally appropriate for them.
There has been an even more pernicious idea bandied about since James Foley's death: that he was responsible for the crime committed against him, because he was too daring a traveller and correspondent.
It was in the nineteen-nineties that restrictions on the use of public benefits by immigrants began, based on the pernicious idea of a clear divide between the deserving locals and the freeloading newcomers.
Given the pernicious idea that the vote to leave was "overwhelming", Brexit means Brexit.
This pernicious idea, of course, came to full fruition during the genocide.
It is time too, to break free from the politics of "community", the pernicious idea that there is this blob of homogeneity.
Over the entire period, more than one in four stories contained the rather pernicious idea that Islam is dangerous, backward or irrational.
