Parashat Ki Tissa is about two profound spiritual crises. To use a Talmudic phrase, shnayim she-hem echad -- two that are really one.
The more famous one is the Golden Calf. When Moshe has been away on top of Mt. Sinai for forty days and forty nights, the people ask Aharon to make them "a god, who will go in front us" (Exodus 32:1). Aharon obliges, creating this idol and proclaiming, "This is your God, Israel, who brought you out of the land of Egypt" (32:4) -- a direct echo of the opening of the Ten Commandments.
The most interesting interpretation is that the people thought the calf was a reasonable representation of their God, the very One whose miracles and words they had experienced. Not another god, but the God encapsulated in a form.
The other crisis belongs to Moshe himself. After pleading to God not to destroy the people, Moshe asks God, "Show me, please, Your Presence" (33:18). The Hebrew word -- kevodecha, usually translated "Your glory" -- comes from the root kaved, which means something heavy, something with substance. God's kavod is God's presence, God's present-ness here on earth.
So here they are, the people and Moshe, really asking for the same thing -- something they can see and perceive in a tangible, palpable way. They are in the same boat. The people, who experience God through miracles and Moshe's own reports. And Moshe, who speaks with God "face to face, as a person speaks with his neighbor" (33:11). Even that is not enough.
To the people, God says no. You shall make no images of Me. To Moshe, God says: "A man cannot see My face and live" (33:20). But also, "I will make all My goodness pass before You" (33:19).
What is the Torah trying to say here? Even Moshe is not satisfied with words, teachings, ideas. But the Torah says: There is nothing a living person can see that would be any truer.
Often people say that they don't believe in God. Usually, it's some particular image of God that they don't believe in. I say image in the widest sense. We've mostly been taught this image: God is the Creator, Who made the universe and operates it, or chooses just to watch. Who speaks or spoke specific words and commands. Who possibly rewards and punishes.
The Torah itself gives us this image. But here, the Torah has God say to Moshe that this picture is not God. If you want to verify that God "looks like" the One who does all those things -- God will not oblige. God has goodness, but even that does not fully define God. God teaches, but even that does not fully define God.
Nothing fully defines God. We sit, like Moshe, in a cleft of rock, seeing only glimpses of some part of God's reality through a covering. Like the curtain over the aron kodesh.
Maimonides compares this to a fire. We can't stare forever directly into a fire, nor can we see what the fire really is. We can feel its heat and the effects of its energy. So too with God. We can perceive the effects of God's energy, though God's essence is obscure.
So like Moshe and the people, we reach for understanding. We hopefully do it with humility. Not seeing God means not tyrannizing or judging others who do not share a particular view of God. Not seeing God means having something in common with others who seek, and with those who study God's teachings and God's goodness (and act on them!). Don't let the God you don't believe in cut you off from God.