Darth Dawkins on the logical incoherence of agnosticism

original: • Video
Here are some clarifications that I should have included.
First, DD is thinking that uttering 'Abraham Lincoln is alive' is a contradiction and incoherent, but it's not. To be an incoherent contradiction you would have to say both the proposition P and not P. To say "Abraham Lincoln is alive" is to say something false, but it is not to say both P and not P, so it's not an incoherent contradiction.
Second, I should clarify what metaphysical possibility means. The use of metaphysical possibility that WLC is talking about is in the context of the modal ontological argument. Modality has to do with concepts like necessity and possibility. In that argument God is defined as a necessary being and has the same modal status as mathematics; if God exists it is necessarily true or necessarily false, and the same can be said of any mathematical equation. The equation 1+1=2 is necessarily true and the equation 1+1=3 is necessarily false. I don't want anyone to mistakenly think that it is a contradiction to say that it's metaphysically possible for Abraham Lincoln to be alive and not alive. What is said here is that there's a possible world where he is alive and another possible world where he isn't. We're not saying that he is both alive and dead in the same world at the same time; we're not violating the law of noncontradictoin. By contrast, it would be a contradiction to say it's metaphysically possible for necessary truths like mathematical equations to be both true and false, because we'd be saying that in all worlds 1+1=2 and in all worlds it's not the case that 1+1=2.
DD says that "when the agnostic speaks he will be speaking from a world where God necessarily exists, or from a world where God necessarily does not exist. In either world he is uttering the possibility which is negated from the reality that he is speaking from [since the agnostic is saying both P and not P are possible]." I don't think he is using the 'necessity' in the modal sense I described. As God is normally conceived, in every world God's existence is either necessarily true or necessarily false, just like mathematical equations. So I'm not sure what DD is talking about; saying there is a world where God exists necessarily and God does not exist necessarily would be like saying there is a world where 1+1=2 is necessarily true and another world where it is necessarily false. My guess is that he's making the same mistake as in the Abraham Lincoln case that to say it's possible that God does not exist in a world where God does exist is to say it's possible that the law of noncontradiction doesn't hold. Recall that DD invoked the LNC and LEM to support his case.
I misspelled 'credence'.