I know that some will attempt to say that, even according to the declarations of our own Scriptures, God is a body, because in the writings of Moses they find it said, that “our God is a consuming fire;” and in the Gospel according to John, that “God is a Spirit, and they who worship Him must worship Him in spirit and in truth.” Fire and spirit, according to them, are to be regarded as nothing else than a body. Now, I should like to ask these persons what they have to say respecting that passage where it is declared that God is light; as John writes in his Epistle, “God is light, and in Him there is no darkness at all.” (From Book I)

What is the nature of God? What is the nature of ultimate reality?

Is God fire? Or spirit? Or light?

The issue here -- at least for Origen and the early church -- is whether or not God has a body or not. The issue emerges as notions of platonic idealism encounter the essentially Jewish worldview of the the church.

Is God corporeal or incorporeal -- with a body or without a body -- which is also a way of asking is God corruptible or incorruptible?

I expect Origen will focus mostly on light, and so do I. But the reality of God might encompass fire, spirit, and light, material and non-material, ephemeral form and ideal form.