Following is a fun video "takedown" of the Kalam Cosmological Argument. It is interesting and worth the see, IMHO.
The "Takedown" of the Kalam Cosmological Argument
However, I wish to approach the subject matter from a different angle...
While Craig asserts that infinity is only a concept that doesn't exist in reality, why does he not afford the same courtesy to nothing? We build logical systems to help us understand and explain the world, but quite often because these logical systems involve boolean values, yea or nay, we assume that these absolute values are entailed by the logical system themselves and, therefore, that they translate into reality or "map onto" reality - but this need not be the case. Concepts like infinity arise from an unending progression and concepts like nothing arise from as idea of a perfect absence. There is nothing to suggest that these "perfect" states exist in reality.
While the video is all well and good, and interesting, I suspect the real "takedown" is in understanding the difference between synthetic and analytic arguments. The Kalam Cosmological Argument is an entirely analytic argument, as is the Ontological Argument.
The Ontological Argument relies on existence being a necessary condition for perfection, but from whence cometh perfection? Perfection seems to me an extension of idealistic thinking, completely divorced from reality, and a mere logical contrast to imperfection. To say that perfection necessarily entails existence is to make a baseless assumption - that perfection is existent or even possible. Claiming that that there is perfection refers not to any feature of reality - please do point to it if you can - but rather to a definition derived entirely from a logical structure - an implication of the terms involved. Nothing more. So when the Ontological Argument goes from "existence is a property of perfection" to "therefore God exists" what we have is an equivocation of the word "exist." Analytic existence is not equivalent to synthetic existence.
More Than One Truth-(Value)
And it is no surprise this happens, since logical "truth" is often equivocated with "empirical" (or "synthetic") truth. We have been engaged in propping up this error for millennia and I suspect this equivocation of truth is responsible for much, especially, theological error. It is, of course, trivia to create a valid argument that is not sound. This proves that logical truth values are not empirical truth. To find out empirical or synthetic truth you actually have to check with reality, something neither the Ontological nor Cosmological arguments do, although they end up making a claim that we are supposed to take as empirical/synthetic.
The nifty thing about entirely analytic arguments is that reality is not a function within them - no empirical reference is made prior to the assertion about reality. In this way terms in the premises represent equivocations of similar terms in the conclusion.
As given in the video, the Kalam Cosmological Argument goes:
Whatever begins to exist has a cause.
The universe began to exist
Therefore the universe has a cause
And that cause is God.
Leaving aside the non-sequitur of the universe having a cause leading to that cause being God... ;)
The real problem here is the word "begins/began." Defenders of the KCA assume that beginning involves arising from nothing, hence their constant mockery that anyone who argues against the KCA is assuming the something arises from nothing. Now a careful examination reveals this to be a mere matter of definition - and analytical function, with no clear reference to reality. The matter seems persuasive because science makes a similar working assumption with regards to causality in order to do its work. However, at no time, does science necessarily invoke the logical concept of nothing in the same way apologists like Craig do (except as an effort to make a dramatic title intended to sell books perhaps). Indeed a recent understanding of the "origins of the universe" seem to posit the idea that there is never really any state of absolute nothing. Hence the "dilemma" presented by the KCA apologists is simply bypassed. And there is no particular reason why this cannot be done, since our understanding of "nothing" is merely the placing of a negation in front of "something." The logical nothing is not necessarily empirical nothing. To confuse them is, in my opinion, to equivocate the word "nothing."
The trick now is to make sure the new physics cosmology refers to empirical reality, and that's where things get interesting. Then it is an exercise in developing experiments from the theory that confirm or refute. We'll know whether the theory is interesting or not when we are provided the falsifiability in the theory.
I am not confident that replacing one entirely analytic argument with another does much for us except display the cleverness of everyone involved. Of course, science provides us the benefit of actually referring to reality - at least most of the time.
Which brings to mind string theory, but that's a topic for another time... ;)