The biggest Dog had always been
The biggest Dog He’d known
He always barked the loudest
And He gnawed the biggest bone
He’d been the highest jumper, too;
He’d been the deepest digger.
He’d always been the biggest Dog…
And then He met one bigger.

How would you know if your god was omnipotent?  Recall Clarke’s Third Law: any sufficiently advanced technology is indistinguishable from magic.  It seems to me, any sufficiently powerful entity will appear omnipotent to a sufficiently less powerful one.

And it wouldn’t really help to simply say your own god is omnipotent by definition; that is, there has got to be a biggest dog, and that’s the one you are talking about.  The problem is simple: you can’t know, from your little dog perspective, whether your big dog is The Big Dog.