here are a few reasons why I think that...
1. He presents himself as being truly unaware of the complexities of the world today. We all saw the news clip with Liebermann correcting him regarding the role of Iran in terrorism.
2. The most frightening piece of that is that he doesn't seem to see the difference between state actors and non-state actors and speaks as if they can be dealt with, excuse me, attacked in the same way. They cannot.
3. His hot temper just isn't the kind of temperament I want in a person who commands the military or especially one who has his finger on the button.
4. he has given up any moral ground that he held before. Read these words from Rabbi Rami Shapiro's blog, Toto, speaking about the Republican Convention... but the comment certainly reflects McCain's current stance
Rather than referencing John McCain’s war record as a sign that he would keep us out of war, rather than pointing to his brutal torture as proof that he would stop America’s use of torture; speaker after speaker glorified war and rumors of war. Rather than use the moral high ground to be moral, they used it to excuse the immoral.
5. He consistently paints the world in black and white, good and evil, us and them. It may play to his base but the real world just isn't that simple.
6. He seems ignorant of cultural and religious differences that are critical for dealing in constructive ways with the Islamic world, a world that is extremely diverse.
I don't believe that John McCain can build the coalitions that are required to work against non-state actors. I don't believe he trusts the power of our example over the example of our power. I don't believe he is able to get past a Cold War type understanding of the world.