truebeliever
nounUK /ˌtruː bɪˈliːvə/
US /ˌtruː bɪˈliːvər/
A true believer is someone who believes in something very strongly.
She is a true believer in the power of kindness.
OTHER MEANINGS
2. A person who firmly accepts a religion or cause.
The true believers gathered every week to pray together.
3. Someone who never doubts a leader or idea, even when others do.
Even after the team lost, the true believers kept cheering.
4. A loyal fan who stays with a group through good times and bad.
The band's true believers traveled to every concert.