Bhagavad Gita, Chapter 18, Verse 7

But the renunciation of obligatory action is not proper. Abandonment of the same from delusion is declared to be Tâmasika.

Giving up real, prescribed duty is named here plainly as delusion, not wisdom.

Krishna doesn't treat all renunciation as automatically spiritual, he calls out the wrong kind directly. Real discernment is required to tell the two apart.