@Old Viking:
But in the thread from which this quote was taken, the prompt for John V's remark was another poster saying "There are no shades of grey in this. All powerful means you can do anything"
Why? Why does having all power automatically mean one has unlimited power? That's not a given. John V's argument, and he restates it several times, is that omnipotent, all-powerful, etc. are not the same thing as "able to do anything."
It would be like saying omniscience must mean knowing 1+1=42, and every other incorrect thing, because if you didn't know them, then you wouldn't know everything. But that's just sophistry, omniscience is knowing all that is knowable, omnipotence is doing all that is do-able.
Where, I think, John V falls down is that he is basically using this argument to answer the problem of evil, that God, despite being omnipotent, could not have created a universe without evil. But, biblically, this is exactly what he did do. Sin only enters creation with the fall, and had God omitted the tree, or the serpent, or even merely placed them in a different garden, there would have been no fall to begin with.