Jewish tradition grapples with this question in some pretty fascinating ways, using metaphors and imagery to try and wrap our finite minds around something truly beyond comprehension. And, honestly, some of the answers are mind-blowing.
Take, for instance, the idea of God's hand. We find in Isaiah 40:12, "Who measured the waters with the hollow of His hand?" The tradition takes this to mean that even God's fist is so immense, so vast, that it could contain all the oceans of the world! Think about that for a second. All the oceans. Held in a fist. We can begin to comprehend the greatness of God from the size of His fist, as it is said.
But it doesn't stop there.
The same verse continues, "and meted earth's dust with a measure." According to Midrash Tanhuma-Yelammedenu, Bereshit 5, this suggests we can also get a sense of God's greatness from the size of His finger. If His finger can measure out all the dust of the earth, how colossal must the rest of Him be?
These images aren’t meant to be taken literally, of course. They’re meant to stretch our understanding, to push the boundaries of what we think is possible. They are not meant to be precise.
And then there's the question of God's dwelling place, the kiseh hakavod, the throne of glory. Even the heavens, as expansive as they are, stretching out beyond the seas, encompassing all the lands, inhabited and uninhabited...even they cannot contain God's throne! It's a truly staggering thought.
Now, there are entire esoteric texts dedicated to describing God's gigantic size and characteristics. The best known of these texts is Shi’ur Komah ("Measurement of the Stature"), and less comprehensive descriptions of God’s size are found throughout rabbinic literature, as here from Midrash Tanhuma-Yelammedenu.
Why this fascination with size? Why this attempt to quantify the unquantifiable?
Perhaps it's because understanding even a little bit about God's immensity helps us understand a little bit about our own place in the universe. When we realize how vast and powerful the Creator is, we also realize how precious and significant each of us must be, to be noticed, to be cared for, to be loved by such a Being.
It's a paradox, isn't it? The bigger we imagine God, the smaller we might feel. But maybe, just maybe, that feeling of smallness opens us up to something bigger than ourselves.