Dr. Craig is a liar.

[Angrboda]

Exactly what do you mean when you say it's inconsistent here?  The idea of God is ridiculous whether or not there is an alternative or not.  To reject a ludicrous hypothesis even if you lack an alternative is not inconsistent, it's just common sense.  What do you mean here?

If you make the statement that nothing necessarily exists, you are also saying that everything is contingent (having an explanation for its existence). If everything is contingent, the universe has an explanation for its existence. 

So the argument seems to be 

1) the universe must have an explanation for existence
2) God cannot be that explanation
Therefore: We don't know, just anything other than God. 

I have yet to hear why the concept of God is logically impossible (and therefore ridiculous).

It isn't that God is an impossible explanation, just that it is a very poor one. Discounting the evidence from miracles, we have no direct effects attributable to this hypothetical being, only the writings and words of men. Explanations are judged on a number of different criteria to determine their merit. One of these is scope, or how many phenomena are covered by the explanation. God gets high marks in this area. Another aspect is parsimony, or how simple the explanation is. Arguably, God fares okay on this metric, though it's hard to compare. On other measures, the God explanation fails miserably. Relevance, or how related the cause is to the effect is poor. Explanatory power, or how well we understand the phenomenon after the explanation as opposed to before is another abysmal failure. Predictiveness, or what predictions you can make based on the explanation and how do those pan out is another big zero for God.

In short, in most of the things we expect a good explanation to provide, God comes up short. God is little more than a Hail Mary hypothesis. It explains everything without explaining anything. The only real advantages it has are scope and familiarity, and familiarity is a lousy reason to support a hypothesis.