I suspect most software developers worth anything will agree that language/technology/editor holy wars are bad. Why specifically though?
A holy war is at its core someone trying to convince you that they know the ‘one true way’. I’ve come to learn in my travels through this industry, and indeed life itself, that there is never ‘one true way’. The real truth is often much more complicated than a single best solution might claim to provide. Furthermore, most holy wars are actually about things that usually are the those that matter the least in the context of great software development. Spaces or tabs, Emacs or vi, newline braces or same line braces; It’s all the same and usually comes down to pure personal preference (though I’ve found most are not willing to admit that is so).
Time is your currency on earth: Spend it solving real problems worth thinking about.