Ami and Makoto are trying to figure out who exactly the Moonlight Knight is. Suspecting that Seijuro and the Moonlight Knight may be the same person, Makoto volunteers to investigate by getting closer to Seijuro.
A religion is a belief system with rituals. The missionary kopimistsamfundet is a religious group centered in Sweden who believe that copying and the sharing of information is the best and most beautiful that is. To have your information copied is a token of appreciation, that someone think you have done something good.