The sky is too big to just call it the sky

Dh was raised lutheran, is biologically half jewish, and practices buddhist beliefs. Gwendomama was raised episcopalian, sent to parochial school, and now a mightily confused agnostic, which is what we say when we are too nervous to take the atheist position....at any rate, rejecting all forms of dogma and organized religion.
When Elijah died, we didn't use the terms 'god' or 'heaven' with Supergirl. We said his body was gone, but the memory of him is not. About a week after he died, we were in the mountains and Supergirl spotted a very large sundog. She decided then and there that it was Elijah and to her, he has lived in the clouds ever since. She always will tell us that Elijah lives in the clouds, and from time to time she will point out the one cloud that is he. Last week, on May 10th we saw another huge sundog over Mammoth Mountain, so I am inclined to believe her.
From hearing others using these words, she has occasionally applied 'heaven' and 'spirit' to her own beliefs.
As open minded and 'enlightened' parents, we of course wish for our children to make their own informed choices about their beliefs and their own paths. But how to expose them to these faiths as options, as a fruit to pick from the tree of their choice - if any - rather than the dogmatic principles that are indoctrinated in the children who venture into sunday school? She's so young, I just want her to be able to see these faiths and practices as choices, and she seems too easily brainwashed at this age (not yet five). I had hoped this would come up later.
But, ahh, parenting...every day a new challenge!!

Yesterday, Supergirl asked me if she could go to church.
Actually, she asked me this:
"Mommy, how old do I have to be to go to high school and church?"
I answered,"Umm, about 15 for high school."
The rest went like this...
Supergirl:Iwould like to go to church.
Gwendomama: Why?
SG: To learn things. And make things.
GM: Like what things?
SG: Well, like art projects and god.
GM: What?
SG: I want to learn about god and make art projects like Beth (best friend). Can I go to Beth's church?
GM: What do you want to learn about god?
SG: Well, I really already know about god. I want to learn other things about god.
GM: What do you know about god?
SG: God is where you go when you die. God is not a person who can talk to you. God is the sky. When you die you go there. But the sky is too big to just call it the sky. Because it has too much stuff in it.
GM: What kind of stuff?
SG: ALL the stuff!!! It has the clouds. And it has the planets and the stars. And the sun and heaven and rainbows. So we call it god.

Now, how can I send her to church? How can I let someone tell her she is wrong about THAT?