I could just as easily assert God is simple.

God is anything but simple. It might seem simple at first, but once you really get deep into theology, you’ll see that God is not simple. There are many good questions about God to really sink your teeth into. I guess you could assert God is simple, but if so you could assert anything simple.

All atheism has to assume is that there is some cause other than a god.

Likewise, all theism has to assume is that there is some cause that is a God.

However, you’re quite wrong about the argument that Dawkins made. He didn’t say it must be complex, quite the opposite in fact. Dawkins said that the first cause must be something simple.

You’re conflating two separate arguments Dawkins made. Yes, he argues that the first cause must be something simple, and I agree. Where you’re wrong is that Dawkins did argue that if we posit a complex designer, that designer also requires an explanation. (TGD p.107) As a response to Aristotle, Aquinas, et al., that is a false argument.

The point is that a god, like my subatomic particles with personalities, is not a simple thing.

I could just as easily assert God is simple.

Yes, and it would also take care of the “Who designed the universe?” question, so there’s no need to ask “Who designed the designer?”, or “Who designed the designer’s designer?” and so on.

If by this you mean to imply that allowing for uncaused entities allows us to posit the universe as an uncaused entity, I’d ask you to define a “caused entity” – then likely disagree.

If we’re talking (a)theism, I think atheism has to assume at least as much as theism.

I disagree. All atheism has to assume is that there is some cause other than a god.

What I ask Dawkins or whoever’s using his argument at the moment is why must we assume that a cause must be more complex than its effect? Something as simple as water caused something as grand as the Grand Canyon.

Good point, you’re quite right about the water, it is indeed simple.

However, you’re quite wrong about the argument that Dawkins made. He didn’t say it must be complex, quite the opposite in fact. Dawkins said that the first cause must be something simple.

The point is that a god, like my subatomic particles with personalities, is not a simple thing.

Then we have the question of whether something uncaused can exist at all. If we decide it can – and one would think that we must – then that takes care of “who designed the designer” just fine.

Yes, and it would also take care of the “Who designed the universe?” question, so there’s no need to ask “Who designed the designer?”, or “Who designed the designer’s designer?” and so on.

In the general case, a hypothesis or theory can be said to be powerful or useful according to what it explains versus what it has to assume in order to work.

I agree. If we’re talking (a)theism, I think atheism has to assume at least as much as theism.

Believers say that all the order and complexity in the world seems unlikely to have come about by chance. So they infer the existence of an intelligent being who brought it about intentionally with some great purpose in mind. Unfortunately the thinking stops there; for some reason they don’t wonder at how the complexity of this intelligent being came about? Such a hypothetical being, with purpose, intent, goals and obviously huge power is quite a complex thing. At least as complex as the universe it is alleged to have created. So the intelligent designer hypothesis doesn’t explain anything, it only adds to the complexity. I’m sure he can’t have been the first, but Richard Dawkins expresses this more succinctly as “Who designed the designer?”.

Although some believers do stop thinking here, I wouldn’t necessarily say the thinking stops there. As an aside, I say the inference of an intelligent being is perfectly reasonable given existence. What I ask Dawkins or whoever’s using his argument at the moment is why must we assume that a cause must be more complex than its effect? Something as simple as water caused something as grand as the Grand Canyon. That’s where the professor befalls himself if you ask me. That the being must be “at least as complex as the universe it created” is an unjustified assumption. It could very well be that the cause of the universe is somehow much simpler than the universe.

Then we have the question of whether something uncaused can exist at all. If we decide it can – and one would think that we must – then that takes care of “who designed the designer” just fine.

Further, even if it were true that whatever created the universe must be more complex than the universe, still, that’s not a cogent argument against God’s existence. Not that you’ve necessarily said as much, either, it’s just that I do hear some people mistakenly trot Dawkins argument here as a disproof.