How powerful is god?

[JuliaL]

Lying isn't a power, it's the result of one not using their brain.

GC

I don't agree that lying is the result of not using one's brain. Some lies take lots of creativity and planning and maintaining them is so intellectually difficult that the benefits aren't generally worth the effort.

However for the sake of argument-
By not using my brain I can do something which the nominally omnipotent god can't.
If omnipotence is defined as the ability to anything possible:
I can, showing the action is possible.
He can't.
Not omnipotent QED.