και γαρ ο θεος ημων πυρ καταναλισκον

Hebrews 12:29 TR - Stephens, Beza, Elzevir and Scrivener all identical.

... for also our God (is) consuming fire.

[Young's Literal and EGNT]

Here, θεος is nominative, there is no copular verb and it seems to me that πυρ is, also, nominative (third declension) with the adjective matching, in the neuter nominative.

Without a verb, what is the grammatical significance of what might be termed the 'equivalence' thus expressed ?

In both of John's similar expressions, he adds the copular verb :

ο θεος φως εστιν I John 1:5 'God is Light'

ο θεος αγαπη εστιν I John 4:8 'God is Love'

Why does the writer to the Hebrews express an 'equivalence' when John does not ?