[from Usenet, but may predate it; common] n. flame wars over religious issues. The paper by Danny Cohen that popularized the terms big-endian and little-endian in connection with the LSB-first/MSB-first controversy was entitled On Holy Wars and a Plea for Peace.
Great holy wars of the past have included ITS vs.: Unix, Unix vs.: VMS, BSD Unix vs.: System V, C vs.: Pascal, C vs.: FORTRAN, etc. In the year 2003, popular favorites of the day are KDE vs, GNOME, vim vs. elvis, Linux vs. [Free|Net|Open]BSD. Hardy perennials include EMACS vs.: vi, my personal computer vs.: everyone else's personal computer, ad nauseam. The characteristic that distinguishes holy wars from normal technical disputes is that in a holy war most of the participants spend their time trying to pass off personal value choices and cultural attachments as objective technical evaluations. This happens precisely because in a true holy war, the actual substantive differences between the sides are relatively minor. See also theology.