Both the pantheistic position and the panentheistic position are unassailable, logically, because they are constructed on the bedrock of axiomatic definition, and the truth of any axiom is as agreed in advance of its application. (Although if Godel is right then all positions are unassailable from within but may be assailable from without).
By way of explanation, let us define something, X, in terms of certain attributes. The definition links X inexorably to the attributes of X, which we ourselves set up, agree, define, create. We create the equation. We establish the axiom. We create the reality.
Consider the following axiom (or definition): There is X, such that Everything That Is, Was, Has Been, Will Be, Could Be (ETI), is X; including things, nothings, thoughts, memories, ideas, rocks, vacuums, quarks, recipes, logic, sealing wax, cabbages, possibilities... anything and everything.
Now let's give X a name. We can name X "Jehovah", or "Baal", or "Beelzebub", or "Lucifer", or "Shiva", or "Vishnu", or "Zeus", or "Aphrodite", or "Mary", or "Gaia" or "Allah" or "Kali" (pictured), or "My Grandmother's Fruitcake", or "A Piece of Snot on the End of my Finger". It doesn't matter what we name X. Having created the axiom in the first place, we can name X anything we like.
In fact, not only can we name X anything we like, we are also free to assign to X whatever attributes we deem fit. We could for instance assign to X attributes related to Ocean (eg wetness, tidalness, waviness, saltiness). And the name we assign to X could be "Poseidon" or even "Neptune".
We could also assign another set of attributes to another thing, Z, and assign to Z a set of attributes including the carrying of the universe upon ones back. And we could name Z "The Great Turtle" (and yes, it is turtles all the way down).
Of course, someone will inevitably say, "We call X in our language "god", and god is wet and salty". And another person from another tribe will say, "you are so terribly terribly wrong; we call Z in our language "god" and god has a very hard shell and can carry enormous weight". And then they will go to war. What a shame. Because they are both right.