Not, alas, a worship of grammar, though it is used to describe grammar-nazis. May be a result of being a grammataster. Or a lawyer. One of a large list of -olatry words of worship (from Greek latreía, service, worship), joined in this case with Greek grammato- (from gramma, letter). Verbolatry.
"The worship of words is more pernicious than the worship of images -- grammatolatry is the worst species of idolatry."
—Robert Dale Owen (1871)---L.