Ok so we hear a lot about how Baze loves Chirrut so much he begrudgingly follows him everywhere, but what about Chirrut?
I’m really fond of the theory that Chirrut was trained as a Jedi youngling but never made the jump to padawan - the masters thought him a bit too impulsive and reckless, nobody wanted to take him on, he didn’t make the cut. So Chirrut spends his adolescence travelling the galaxy pretty aimlessly and taking whatever weird job they throw at him (he bailed on the service corps or whatever the official programme is - i forget the name - after six months and did his own thing)
So Chirrut ends up, a lanky lad of eighteen, on Jedha, doing odd jobs, cheating people when gambling through improper use of the force, grinning and improvising his way through life until he gets bored, he’s about to smuggle himself out on the next shuttle in about an hour - until he spots the most beautiful temple guard he has ever seen in his life? Like wow. He’s gorgeous and holy shit. There’s no way he’s leaving now - he’s gotta get his attention somehow how, he’s gotta talk to that guard, otherwise he’s gonna regret it for the rest of his life.
tl;dr Chirrut Imwe is inducted into yet another religious order because he’s got a gigantic crush on Baze Malbus and needed an excuse to stick around.