it is referred to as the "church" grim as it was an English folklore creature who guarded the graves (owned by a church in that period of time) against evil spirits. Myth had it, that the first body buried was responsible for guarding the graves, and the people thought it was unfair that people should take on this role rather than resting in peace. So at many newly established grave sites, a live animal (large black dog) would be buried alive.
Many church grims are well know to ring the church bells, and often, a death in the community soon follows. Many popes/bishops have accounts of being able to tell if certain bodies are going to hell or heaven based upon the expression on the grims face. Sometimes, the grim is seen as an omen, it is said that if someone is to look into the eyes of a grim three times in a row (in three encounters) they will die shortly afterwards.
Overall its a pretty cool concept, and you can probably see a few resemblances between the grim and Sirius Black in dog form from harry potter (did i mention grims like lightning?) Anyway, the picture Ive posted below was a devian art work, i just thought i should mention, as this anonymus artist deserves credit for their work. (which was found in google)
