For Christians (or anyone else) who deny Darwinian evolution.

[Succubus]

You don't need a Cray computer to perform basic arithmetic functions, and you don't need a massively complex neural system to invoke a reflex action to a stimulus. No doubt you will now ask 'how could they evolve together'?
The answer is; they almost certainly didn't. It is highly likely the first hundred trillion of these creatures with their proto eyes and proto nervous systems did not have the two synchronized, not to the benefit of the creatures survival that is.

It's highly likely this primitive arrangement at first resulted in the creature freezing when light hit its proto eye and gained no evolutionary advantage. Now fast forward a ~million? years. A handful of UV photons hits the light sensitive patch and whatever passes for a muscular system goes 'kick' and the thing darts off to one side.
What happened to the recalcitrants, the first group? They were eaten!
Evolution in action.

First, recognizing shapes and reacting to them is way way way more complicated then "moving toward the light". It would involve some sort of memory, some sort of if-then-else logic, and some way effect enough movement to make a difference. 

Correct. However, the first organisms did not have the ability to recognize shape, that came a ~million? years later.

You are positing two beneficial mutations that developed brand new functions simultaneously happening...eventually.

Asked and answered, the two mutations would be of no benefit until they were synchronized and that took ~millions? of years.

Then when the organism moved from just light sensing to shape sensing, two new beneficial mutations simultaneously happened as well (one in the "eye" and the other in the nervous system)--because neither the ability to "see" shapes nor the ability to process shapes had any survival benefit until the other was functioning.

Incorrect. From light sensing to shape sensing probably took a million mutations not two, and 999,999 of them failed. It appears you are asking for a mutation by mutation  account of the evolutionary process, no that can't be done.

But we still have a problem. Just sensing the light and processing the sensory information is not enough to confer a survival benefit.

I'm sure I covered this. If you are an amoeba like creature sitting under the sun in a warm pool and suddenly the light goes out, that means something just moved between you and the sunlight. Something bigger than you. Remain still and be eaten like a thousand trillion just like you.
Then something happened which unleashed the power of their imagination survival, they learned to move.

The organism must be able to do something about it.

It doesn't have to do any such fucking thing! You are still talking as though evolution has a goal, it doesn’t. A billion trillion of these things appeared and then disappeared  because they were not fit to survive the prevailing conditions.

Your description could be right. The point I have made 20 times already in this thread is that we really don't know how these things happened.

It's called natural selection, I think someone may have mentioned it in this thread.

If we don't know how, it cannot be a scientific fact. If it's not a scientific fact...

Begging the question.

...it is a philosophical claim that it happened.

 
The fact that you don't understand how it works doesn’t mean others don't, all it means is; you! don't understand.