Dr. Craig is a liar.

[SteveII]

The biggest problem P1 has, as far as logic goes, is that it is guilty of the fallacy of affirming the consequent. 

To break it down:

The statement, "Everything that begins to exist", is another way of saying, there are 2 sets: one set contains everything that  begins to exist, the other set contains everything that does not begin to exist. 

The theist making the argument only believes that one thing, their god, is a member of the set of all things that do not begin to exist.

So, their god is inserted into the first premise, and is also the conclusion of the argument. 

Without even getting into the soundness of the premises, the modus ponens of the argument is flawed.

I don't think it is affirming the consequent. That fallacy is 

1. If P, then Q.
   
   
2. Q.
   
   
3. Therefore, P.
   

Perhaps you think it Question Begging? – providing what is essentially the conclusion of the argument as a premise.

If that is the case, that has been addressed:


Objection #2: The kalam cosmological argument is question-begging. For the truth of the first premise presupposes the truth of the conclusion. Therefore the argument is an example of reasoning in a circle.

Response to #2: All the objector has done is describe the nature of a deductive argument. In a deductive argument, the conclusion is implicit in the premises, waiting to be derived by the logical rules of inference. A classic illustration of a deductive argument is:

1. All men are mortal.

2. Socrates is a man.

3. Therefore, Socrates is moral.

This argument has the same logical form as the kalam cosmological argument.[5] In fact, this form of the argument even has a name. It is called modus ponens. Symbolically, it looks like this:


This is one of the most basic and important logically valid argument forms. Incredibly, I have actually seen claims by Internet critics that this argument about Socrates being mortal is also question-begging!

This raises the question of what it means for an argument to be question-begging. Technically, arguments don't beg the question; people do. One is guilty of begging the question if one's only reason for believing in a premise is that one already believes in the conclusion. For example, suppose you were to present the following argument for the existence of God:

1. Either God exists or the moon is made of green cheese.

2. The moon is not made of green cheese.

3. Therefore, God exists.

This is a sound argument for God's existence: its premises are both true, and the conclusion follows from the premises by the rules of logic (specifically, disjunctive syllogism). Nevertheless, the argument is not any good because your only reason for believing the first premise to be true is that you already believe that God exists (a disjunction like premise (1) is true if one of the disjuncts is true). But the belief that God exists is the conclusion of the argument! Therefore, in putting forward this argument you are reasoning in a circle or begging the question. The only reason you believe (1) is because you already believe (3).

Now neither the argument for Socrates' mortality nor the kalam argument is like this. In both cases reasons are given for believing the first premise which are quite independent of the argument's conclusion. Biological and medical evidence may be marshaled on behalf of the premise that all men are mortal, and I have presented arguments (which I'll review shortly) for the truth of the premise that everything that begins to exist has a cause. Therefore, I have not begging the question. The objector has made an elementary mistake of confusing a deductive argument with a question-begging argument.

Read more: http://www.reasonablefaith.org/media/obj...z48C7JPnyn