Holy war is a perpetual passionate argument over usually two possible choices. This separates people into almost religious teams that sometimes argue to death about details such as what name something should be given, very much resembling traditional disagreements between religions and their churches. In holy wars people tend to defend whichever side they stand on to the death and can get emotional when discussing the topic. Some examples of holy wars are (in brackets indicated the side taken by LRS):
Things like cats vs dogs or sci-fi vs fantasy may or may not be a holy war, there is a bit of a doubt in the fact that one can easily like both and/or not be such a diehard fan of one or the other. A subject of holy war probably has to be something that doesn't allow too much of this.
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