If, then, they acquiesce in our assertion, which reason itself has demonstrated, regarding the nature of light, and acknowledge that God cannot be understood to be a body in the sense that light is, similar reasoning will hold true of the expression “a consuming fire.” For what will God consume in respect of His being fire? Shall He be thought to consume material substance, as wood, or hay, or stubble? And what in this view can be called worthy of the glory of God, if He be a fire, consuming materials of that kind? But let us reflect that God does indeed consume and utterly destroy; that He consumes evil thoughts, wicked actions, and sinful desires, when they find their way into the minds of believers; and that, inhabiting along with His Son those souls which are rendered capable of receiving His word and wisdom, according to His own declaration, “I and the Father shall come, and We shall make our abode with him?” He makes them, after all their vices and passions have been consumed, a holy temple, worthy of Himself. (From Book I, section 2)

For Origen, Fire is less "body" than process. So God is more fully analogous to fire than to light.

Light emerges from a body -- sun or moon -- that is physically specific and limited. When the body disappears, so does the light.

Fire, in contrast, can extend far beyond its point of origin. As a process, fire has no corporeal limits.

Light illumines but does not otherwise affect objects encountered. Fire consumes all in its path.

But fire destroys, while light is essential to growth. Origen has not - yet - persuaded me that fire is better than light in understanding the nature of God.