Wiktionary
believed in
vb. (en-past of: believe in)
Usage examples of "believed in".
In the end a hunch was a hunch, and either you believed in your hunches and played them or you didn't.
He also believed in what he was doing, and he was just as sure that it was right.
It was apparent that that "code" was what Rojan lived by, and that he believed in it unshakably.