Be salaried by the Japanese government to teach English in a junior high or senior high school in Japan! Fairly strict requirements. Say Yes to Japan can help applicants locate a nearby missionary/church.
JET also hires a very limited number of people to serve as “coordinator for international relations” and “sports exchange advisor.”
There is a JET Christian Fellowship group that helps Christian teachers get the most out of their JET experience. Check out their site or find them on Facebook.