Someone in a previous congregation told me that Crystal Blue Persuasion was written about The Truth (That Leads to Eternal Life) book. I never did find out if that reference was true or not.
But back to the topic, if we dared to listen to anything but kingdom melodies, then classical music was always ok. Anything that mentioned evil, devil, demons was obviously bad, but so were things that mentioned God / Jesus, because they all had all stemmed from wrong teachings.