The term "True Believer" is a popular culture reference that originated from the 1950s and refers to someone who has strong, unwavering belief in something or someone. The phrase was coined by author Nicholas Monsarrat in his book “The Cruel Sea” published in 1951, where it described a character’s dedication to their cause despite the odds stacked against them.
Since then, the term has been used in various contexts including politics, religion and popular culture. In general usage, "True Believer" refers to someone who is deeply committed to a particular belief or ideal, often going beyond rational thought or evidence to maintain their conviction. The phrase can also be used ironically to describe someone who is overly enthusiastic about something without necessarily having strong reasons for their beliefs.