true believer

American  

noun

1. a person who has been thoroughly convinced of something.

2. a fanatic, especially a religious or political one.

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Example Sentences

And so you have to have a leader that is a true believer, so that sort of mentality trickles down.

From The Wall Street Journal

But what matters for Fed independence is that Hassett is a true believer in it, says Harris, the Fed watcher.

From Barron's

He is what you might call a bitcoin true believer.

From BBC

When Stephen Scheeler became Facebook's Australia chief in the early 2010s, he was a true believer in the power of the internet, and social media, for public good.

From BBC

Taub is a true believer in the democratic process, and in the power of a unified populace to effect real and lasting change.

From Los Angeles Times