cobeliever
/koʊbɛlˈiːvər/Definitions
1. noun
a person who shares the same faith or beliefs as someone else, especially a partner in a romantic relationship.
“As a devoted co-believer, she stood by him through thick and thin.”
2. verb
to share or hold the same faith or beliefs as someone else.
“After getting to know him, she began to co-believe in the same spiritual practices.”