The phrase "an existential peril" is correct and usable in written English.
It can be used to describe a significant threat or danger that affects existence or survival, often in a philosophical or global context.
Example: "Climate change poses an existential peril to our planet, threatening the very foundations of life as we know it."
Alternatives: "a fundamental threat" or "a critical danger".
Nobody can be quite sure that in a corner, confronting what it believed to be existential peril, Israel will not act alone if necessary.
Yet the existential peril facing Iraq, the scene of a 2011 US pullout, has led legislators to predict that the Taliban will overrun Afghanistan in the face of a similar US withdrawal.
Brutal state-legislative redistricting after the 2000 census left several of Governor Bush's Democratic allies in existential peril.
To my mother's and my grandmother's generations, the Party is what saved the nation from existential peril.
Hecht is cited in "Almighty: Courage, Resistance, and Existential Peril in the Nuclear Age" by Dan Zak (Blue Rider Press, 2016).
In times of "existential" peril, as Britain's fate hung in the balance, step by step, Lewis clearly explained how a sense of moral obligation can't be explained by what he called instincts of self-preservation or allegiance to the herd.
Redstone's other high-profile holding through National Amusements, CBS, fared far better under its own chief executive, Les Moonves, who is widely perceived as having dealt with the existential perils of cord-cutting and a fragmented cable landscape better than his competitors in the broadcast TV world.
Both are raving hawks who warn of the existential perils of significantly reducing military spending.
"My party is in peril, we are facing an existential crisis and I just don't want us to be in this position because I think there are millions of people in this country who need a left-leaning government," told BBC News.
"My party is in peril, we are facing an existential crisis and I just don't want us to be in this position because I think there are millions of people in this country who need a left-leaning government," Watson told BBC News.
