"Spook," spectre" or "phantasm?" Mine is "spook" because it's pretty specific and unique to dialectical egoism. And you can also play with it by adding prefixes and postfixes (i.e. spooked, despooked, unspooked, spooky, reverse-spooked, anti-spook, spookprejudiced). I also like to say "sacred idea" or "ghost in the mind" sometimes.