http://en.wikipedia.org/wiki/Pillar_of_Fire_%28theophany%29
Exodus 13:21-22. By day the Lord went ahead of them in a pillar of cloud to guide them on their way and by night in a pillar of fire to give them light, so that they could travel by day or night. Neither the pillar of cloud by day nor the pillar of fire by night left its place in front of the people. Exodus 14:24. During the last watch of the night the Lord looked down from the pillar of fire and cloud at the Egyptian army and threw it into confusion.
So God himself shows up in front of Israelites as a pilar of fire.
That means:
- God sometimes materialize (at least visually), as a pillar of fire
- God can be seen (at that time as a pillar of fire)
Is it okay to worship that pillar of fire because the Torah itself says the pilar is God?
Of course, secularists would say that the pillar is just an erupting mountain.
Even if it's not, it'll still be just one of God's hologram/theopany/illusion/show, which mean it's still God's creation.
So is the pillar God's creation, or God' himself?
related question: If God was never incarnated, how come He sat in front of Abraham's tent and appeared among the oaks of Mamre?
If God can show up as pillar of fire, what would stop Him from showing up as humans?