Dr. Craig is a liar.

[Time Traveler]

Why do you think God needs to "think" about anything prior to creation? 

Steve, this is idiotic. It is YOU that brought up the notion of God thinking prior to creation, not me! Let's review your words (p. 29)

If timelessness is not an essential, but rather a contingent characteristic of God, God could have decided to exist timelessly in the past and then decide to create the universe and in doing so became temporal.

and here... (p.38)

Even a series of mental events is enough to form a before and after (therefore some measure of "time").

So the question is, why do YOU think God needs to think/decide/have a series of mental events prior to creation? Why do YOU think there was some "before and after (therefore some measure of "time")" contrary to Craig's assertions?

Why can't causation be simultaneous with its effect?

1) Define cause and effect.
2) Demonstrate simultaneous cause and effect is plausible under your definition.
3) Even if we grant whatever you mean by simultaneous cause and effect, you still can't get around the fact that, God could not exist timelessly and changelessly without the universe prior to causing time to exist within the universe. This is a non sequitur.

Why does causation presuppose the existence of time? 

Review the first video in my "Timelessness" thread here: http://atheistforums.org/thread-42797.html
Time becomes an emergent property of causality. Or, put in terms of the video, "Causality is responsible for Time."

Why can't God become temporal the moment there was something to have a temporal relationship with?

That's not the question. It has never been the question, as I've stated emphatically before. It's the question you want to answer, but it's not the question being asked. The real question, which I'll try to state again in another way borrowing some of your words is, How could God ever exist atemporally prior to the moment there was something to have a temporal relationship with? If he did not ever exist atemporally, if God's first moment was simultaneous with the beginning of time within the universe, then God has never been anything other than temporal.

You misunderstood the sentence: "The image of God existing idly before creation is just that: a figment of the imagination." The point was NOT to imagine God sitting idly.

No, you misunderstand the mixed message Craig is stating. When Craig expresses that God was ever extant "timeless without creation," in a "changeless, undifferentiated state," one MUST picture "God existing idly before creation." Because if God did not exist in a timeless, changeless state sitting idly before creation, then God either 1) was NOT timeless or changeless before creation, or 2) Had a beginning simultaneously with the universe.

I'll try to make this clear to you once again: If God ever existed in a changeless, undifferentiated, timeless state without creation, then this necessarily happened prior to/before creation; anything that happens prior to/before something else defines two different states; a causal relationship between two different states is a measure of time and therefore cannot be timeless.

Let's try two simple Yes/No questions based on our discussion, addressing the implications of each answer:

1) Did God exist timelessly and changelessly by himself, prior to the creation of the universe?
1a) If Yes, then by definition, something that is changeless cannot change, something that is timeless will never transition from one state to another; therefore, God could not have logically been the agent of change, and could not have transitioned from a (timeless + no universe) state to a (temporal + universe) state.
1b) If No, see question 2.

2) Was God's existence simultaneous with his creation of the universe?
2a) If Yes, and if the universe had a beginning as theists' assert, then God had a beginning at the exact same moment as the universe. If two things can begin to exist at the exact same moment, and we have empirical evidence for one (the universe) and absolutely no evidence for the other (God), then we can safely excise the latter as wholly superfluous.
2b) If No, then God must have preceded the universe, see question 1.

Steve, I can't tell if you really don't understand the blatant contradictions within Craig's arguments, or you are just being disagreeable and purposefully deceptive at this point, like William Lane Craig often is. Any way you look at this, a timeless/changeless being can't implement change, and therefore this imagined deity can't be the explanation for anything.