A few (maybe optional) standards I can think of when deciding what to avoid are:
- Avoid things that would detract from the sacred. By that I mean lyrics that would create mental associations that would distract you when trying to engage the sacred.
- Anything that could lead to lust. This would also extend to music videos, some of which can be rather sickening.
- Any song that might be used as a way to fuel anger against God, particularly in moments when you’re struggling with faith.
One thing all of those have in common is that the song can lead you to actual sin. So basically, just avoid what may lead you to sin, but the above three are, in my experience, the most obvious ways.
I guess the main concern otherwise would be actual occult influences in the lyrics. As an example, Dimmu Borgir’s Abrahadabra is basically a love letter to Aleister Crowley, even down to its name. In contrast, Carach Angren’s Dance and Laugh Amongst the Rotten makes clear references to occult practices but presents them as avenues of evil meant to drive the album’s story. Personally, I would steer clear of the former, but I have no problem with the latter.