My shortest explanation of buddhism yet:

for any X, if there is an arising of X it follows that (abayakata)

X exists forever is False
X does not exist forever is False
X both exists forever and does not exist forever is False
X neither exists forever nor does not exist forever is False

for any X, if there is an arising of X it follows that (magga)

there is an arising of X is True.
there is a cessation of X is True.
there is a path from A (arising) to C (ceasing) is True.

Thoughts?

You need to show this is true for all X excluding nibbana, else what you’ve described could apply to a theistic religion

No, nibanna merely refers to the extinguishment of Xs, nothing furthur, nibanna is not

Eternal
Momentary
Both
Niether

Nor is it an arisen X, by definition.

Sure, but you still need to show this is true for all X and not just a subset.