false sense of security

Translations
ложное чувство безопасности
The locked door gave them a false sense of security.
Запертая дверь дала им ложное чувство безопасности.
Definitions
A false sense of security refers to a situation where someone feels safe or protected, but in reality, they are not. This illusion of safety can lead to complacency and a lack of preparedness for potential dangers or risks.