"{not} [have] a (single|) prayer" 的定义和意义

What is the origin of the idiom "not have a prayer" and when to use it?

The origin of the idiom "not have a prayer" is uncertain, but it may be related to the idea of prayer as a form of supplication or appeal to a higher power for help or mercy. The phrase has been in use in English since at least the mid-20th century, and it has been applied to a wide range of situations, including personal and financial struggles, legal cases, and sports competitions. In general, the phrase is used to describe a situation where success is so unlikely that even divine intervention would not be enough to bring it about.