Baze Malbus is a human freelance assassin from the moon of Jedha, a former Guardian of the Whills, and one of the six who die on Scarif in Rogue One: A Star Wars Story (2016). Jiang Wen plays him.
The unbeliever
The Guardians were the warrior-monks who protected the Temple of the Kyber on Jedha. Baze was one of them. By the time the film finds him the Empire has stripped the moon of kyber for the Death Star, the temple's order is finished, and Baze has replaced his faith with a repeating cannon. He is openly contemptuous of the mantra his companion Chirrut Îmwe keeps reciting.
The pair
What makes the character work is that his cynicism is entirely aimed at the Force and not at all at Chirrut. He follows a blind man into every fight on Jedha, Eadu and Scarif without once suggesting Chirrut should stay behind. The film is economical about their relationship and never labels it; what it shows is two people who have been together long enough that one of them stopping believing changed nothing.
Scarif
He takes up the mantra himself, out loud, only after Chirrut is killed — walking into fire reciting words he has spent the whole film mocking. He dies moments later. It is the most direct statement Rogue One makes about what faith is for, and it is delivered by the character who did not have any.