The difference between active and passive is not whether there is an 'action' but the syntactic role of the person or thing 'acted upon'.
In a sentence cast in the active voice, the subject is the Agent - the 'doer' - and the direct object is the Patient - the one 'acted upon' or 'done to'.
Agent loves Patient.
When that sentence is recast in the passive voice, the Patient becomes the subject and the Agent disappears, or is relegated to a prepositional phrase.
Patient is loved [by Agent].
So intransitive verbs - verbs which do not take a direct object - cannot be cast in the passive voice, because there's no Patient to become the subject of a passive sentence.
Agent dies. ... there's no Patient who can ✲'be died by'!
BE is an intransitive verb: it has no Patient, only an Agent to whom some quality is imputed, so it cannot be cast in the passive voice. It is always active.
✲ marks an utterance as unacceptable