Can anyone help explain Sharon Olds poem "Culture and Religion"?

When the witch flew up to the left right left I
Remembered it- wasn't there something
Sharp which had soared into the sky on a spiral
like that over Jerusalem? The only other
movie I had seen, every Good Friday,
was the Crucifixion documentary,
noon to three, and wasn't
this the cloud-cover, from over the crosses,
their delicate shapes thickened and distorted,
stuck with their grievous human gum,
above them the liquid dart of the witch
streaked. And wasn't the witch\s home,
near Oz, Golgotha? Her broom had been the stick
on which they had stuck the vinegar sop, I
recognized it, the same prop, and the
field of poppies, wasn't that
Gethsemane? And the witch wanted
To torture them to death, like Jesus
-blood, tin, straw- what they
Were made of was to be used to kill them.
And she lived on a hill, like Calvary, where the
Crosses stuck out like pins from the globe – or
Would it have been worse in a pit, look down
And see the crosses set up below us
In the scooped-out fruit if the earth. And parts
Of the castle looked Roman, as if Dorothy
Were back in the underpopulated time, the
Eerie empty world. But what was
That harsh projectile scrap of cinder which
Pulled across the screen, turned, reversed,
And was sucked up? Nothing went up, that
Day, off the tussock of execution,
They brought him down, to the ground, down
The hill, laid him down, in the tomb
-and yet when the Wicked Witch of the West soared
Up, it was over the Crucifixion, there
Must have been a piece of fluff on the
film or a disc of soot pointed like a
burnt thing, caught in an updraft.
I remember when Jesus died the trees
Bent and groaned, there was a strong wind, we were murderers