The second thing we know about Hashem is really an off-shoot of the first (His having no cause). That is, His simplicity. Even though we say that Hashem has infinite strength, wisdom and goodness (to mention just three of His attributes), we do not mean that statement literally, any more than we mean “G-d let the Jews out of Egypt with an outstretched hand” literally.
Just as G-d has no hand, so too He has no strength, no wisdom and no goodness. He has no components. If he would have components, the combination of those components would be the cause of Him (since without some or all of those components He would be different or non-existent), and He has no cause.
But now the question arises: If Hashem has none of these attributes, doesn’t that mean that Hashem is imperfect? How can a perfect G-d have no strength, no wisdom, and no goodness?
The answer is that G-d has no strength because He doesn’t need strength; no wisdom because He has no need for wisdom; no goodness because He has no need for it.
Strength is only necessary when there is something for you to pit your strength against. If someone can lift 400 pounds it means he can overcome 400 pounds of resistance. Strength is a compensating force that allows you to overcome opposition.
If there is nothing capable of presenting resistance to Hashem, saying that He is “strong” is absurd.
Wisdom is a tool used to figure things out; knowledge is the thing you use to overcome ignorance.
G-d doesn’t need any of these things. Indeed, He cannot have them; they make no sense in the context of Hashem.
G-d is not ignorant even though He has none of what we call "knowledge" – so He doesn’t need knowledge. He is not weak even though He has none of what we call "strength". G-d doesn’t need the assistance of these compensating abilities because He has nothing to compensate for.
“All-powerful”, when we apply it to Hashem, does not mean quantitatively more powerful than you and I. It's not that Hashem has more power than anyone else. Hashem's power is completely different than what we understand power to be in this world.
Power, to us, means the ability to overcome something. Perhaps to lift weight (overcoming resistance), to jump high (overcoming gravity), or to figure out a mystery (overcoming lack of knowledge).
Limits come into the picture when the power that we want to overcome is greater than the power we possess. A limit means that there is some other power greater than yours.
Power and limits are expressions of the same thing. It's just a matter of how much power there is.
None of this makes sense when it comes to Hashem. When we say, “Hashem is all-powerful” it doesn't mean that He has power like we have except that He has an infinite amount of it. That would mean that the difference between Him and us is that we can only overcome a limited amount of things, but He can overcome everything.
Nope. That's not the idea. It's not that He is stronger than any power, but rather that He is the only power. There is no opposing external force for him to vanquish, since He is the creator, maintainer, and controller of all power in the world.
If you want to say that Hashem does have limits, I would ask you what the source is of the power that you say is stronger than Hashem. Since we can prove that the world - the entire world - has a creator, then the power that you claim is stronger than Hashem also must have a creator. Which means, ultimately, that the creator of the world can have no limits, since He would be the creator of power as well. And if you create and control all power in the world, you cannot have any limits, because limits means there is a power stronger than you.
When you understand how Hashem created the universe, you realize that He must be all-powerful. Not because he has more power than anything, but because there is no power except Him.
Hashem is called “Makom"” (place). The reason, Chazal say, is because “The world is not a place for Hashem, but rather Hashem is a place for the world”. This means that the entire world, the entire universe - reality itself as we know it - is only an expression of Hashem's will.
A good way to understand Hashem's existence versus ours (only as a moshol, a parable, of course) is to imagine a little world that exists only in your mind. Little people, little cities, little rivers and forests - all in your imagination.
This is a moshol to explain how Hashem created the world. Those people in your mind have real existence - they are little electrical impulses in your brain, which are involved in your thought process -but compared to you, they don't really exist at all.
So too we exist in some way, but only as expressions of the Will of Hashem. “Ain Ode Milvado” - there is nothing except Hashem. “This means nothing has true existence like Hashem” (Rambam Yesodei HaTorah 1:4).
In your imaginary world, there would be no such thing as you having limits on the power you possess. Since the entire thing is only an expression of your will, no power there can exist without your desire. It would make no sense to question whether you are “strong” enough to lift a big rock in your world or to revive someone from the dead, since the rock is only heavy by your will and the person is only dead because you imagined it so.
Your will controls everything and so no force exists except you.
When we say Hashem is all-powerful, we do not mean that He is stronger than anything, but rather there is no strength at all in the entire world except Him.
This is the simple meaning of “Ain Ode Milvado.”