The Jargon File (version 4.4.7, 29 Dec 2003):

holy wars
 n.

    [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.


The Free On-line Dictionary of Computing (30 December 2018):

holy wars

   [Usenet, but may predate it] flame wars over religious
   issues.  The paper by Danny Cohen that popularised the terms
   big-endian and little-endian was entitled "On Holy Wars
   and a Plea for Peace".  Other perennial Holy Wars have
   included Emacs vs. vi, my personal computer vs. everyone
   else's personal computer, ITS vs. Unix, Unix vs. VMS,
   BSD Unix vs. USG Unix, C vs. Pascal, C vs. Fortran,
   etc., ad nauseam.  The characteristic that distinguishes holy
   wars from normal technical disputes is that in a holy wars
   most of the participants spend their time trying to pass off
   personal value choices and cultural attachments as objective
   technical evaluations.  See also theology.

   [Jargon File]