William Lane Craig argues that we have good reason to believe that the universe had a temporal beginning, and that the Big Bang theory shows this. What that means is that the Big Bang theory, which in popular culture is presumed to be an atheistic theory, is actually embarrassing for atheism, since it agrees with the Bible that there WAS a beginning. [source]
Let's put aside whether Craig would agree to the above (I think he would), the problems with the argument are:
1. Layman's understanding of Big Bang Theory should be that at the Big Bang, it was a singularity. That is we have no physical means to know what was before the Big Bang. Stephen Hawkings have recently established that Big Bang will spontaneous appear under the law of Quantum Physics. Universe is not caused. Ignoring the latest understanding and cherry picking of Science to support a view is a logical fallacy.
2. The bible may be right at one thing - the universe has a beginning. That does not imply the rest of the bible is also correct. Take the sequence of creation as an example. The bible is complete wrong. To judge a claim to be right or wrong, we depend on evidence to support that claim. A lucky guess is just a lucky guess. Nothing special.
Craig maintains what whatever begins to exist, must have a cause of its existence, and since the universe began to exist, the universe has to have something other than itself cause it to exist. On the other hand, God, according to the definition, never began to exist, so he needs no cause of his existence.
1. The claim that "what whatever begins to exist, must have a cause of its existence" needs evidence and proof. To prove this statement is wrong, I only need ONE counter example. Here it is. From Quantum mechanics, we know that radioactive exists. The instance at which a radioactive nuclei decays cannot be predicted. We can only have statistical laws about radioactive decay. This is an example of event without a cause. If this event has a cause, we would understand precisely the moment when the cause is satisfied and would trigger the decay. Heisenberg uncertainty principle implies that it is impossible to know the cause and hence the event is strictly uncaused. Of course, the second counter example would be the appearance of our universe.
2. By definition god does not need a cause is another example which I could use to disprove the claim that "whatever begins to exist, must have a cause of its existence". God, if exists, has existed. There is no obvious reason, except by the trickery of words, to define it as needing no cause. The fact is that we do not know whether god exists because of a cause. This would need to the recursive situation of a god' creator and ad infinite. This is an obvious logical impossibility. Either god exists without a cause OR god does not exist. This argument does not exclude the possibility that the god in our definition does not exist.