Ok, you maintain that it is the winter solstice, ok, I get it.
You also maintian that because of the phrase " a tree in its firmness" it means that the tree had roots. Now, how do you carry a tree with its roots being firm, and christmas trees definately do not have roots.
In addition to this, as I tried to point out, there was worship of a goddess in which a tree or a grove of trees were planted.
I would ask you to show some evidence that the tree was involved in the winter solstice and only the winter solstice.
In addition there are many pagan customs involving trees, look up about the mayan world tree, the norse oak, the oak and holly trees for druids, the acacia tree for several cannanite godesses, or the laurel tree for the romans. I would ask for proof that this particular pagan ritual had something substantially similar to our christmas tree.
I also would ask that you look up some information on Ashera or Astarte, and see if that could be closer to what Jeremiah was talking about.
A lone Raven