When a pacifistic Christian missionary is sent to a war-torn village in ancient Japan, he tries to spread peace to the two divided clans, only to discover a greater threat from the tyrant shogunate that faith alone cannot cannot stop. He must unite the clans and take military action to finally bring peace to the village.

Video game? Make the movie! I want to see it immediately!!

It is a slightly long logline, I think you could trim the odd word here and there: maybe try something like “Ancient Japan: when a pacifist Christian missionary tries to make peace between two warring clans, he discovers…” etc. But the idea itself is rock solid, and has huge potential.