The coming clash will not be between Muslim and Christian nor between East and West nor between rich and poor.
There are tensions between all of these 'camps', for sure.
The poor have nothing to fight us with and so there can be no 'clash' with them. I believe, however, that the 'San Bushmen and the Yanomani and the Aboriginals will be on the planet long after the last trader's screen blinks off on Wall St.
The East sees little reason to change its growth plans as they have not caused the existing atmospheric carbon increases. The West is being miserly in its offering of technology and resources that might help the East avoid the worst of the West's environmental excesses. I expect, however, that as the catastrophe unfolds both sides will be driven into each others' arms as the real 'globalisation' emerges.
The tension between Islam and the Christians is a proxy for the economic and political serfdom that the “Ummah” has suffered at the hands of the British and then American empires since the collapse of the Ottoman empire. The resentment of, and terrorism against, the 'infidel' comes from those states where the populace has been denied political expression and economic development by puppet regimes of the 'West', which has at the same time looted those countries of their natural resource (crude oil). For proof, compare the peoples of Turkey and Saudi Arabia. There were no Turks on the 9/11 planes and there are none fighting in Iraq or Afghanistan.
So, the conflict between Islam and Christianity is in reality the same as the Northern Irish conflict between Protestant and Catholic; a proxy for a historic battle for economic resources.
So, in the coming struggle, who will be doing the fighting?
The conflict, I expect, will be between the enlightened and the ignorant.
Fear, uncertainty and doubt will be wielded as weapons by demagogues, cynics and the vocal ignorant promoting simple solutions against the complex analysis offered by the reasoned, the reasonable and the eloquent as defenders of truth, hope and knowing.
Ignorance and false knowledge (such as theology) are being used to pervert the minds and recruit the bodies of the gullible, the ignorant and the desperate in every corner of the planet.
For each madrassa in Pakistan, there is a creationist college in the US. For each witchdoctor in the Congo, there is a neofascist skinhead in Moscow. For every bureaucrat, there is a copyright lawyer.
But these are not in opposition to each other. They are united in their opposition to those who believe in tolerance, openness and freedom.
For every Buffet and Jobs there will be an Ellison and a Murdoch. For each Mandela there will be a Putin. For every Dawkins there will be a Limbaugh. For each Obama there will be a Mugabe. For every Pelosi there will be a Palin.
The 'Dark Ages' did not lack for daylight. They lacked knowledge and the means to transmit knowledge. But the greatest impediment to progress were elites who fought to keep knowledge and enlightenment out of the hands of the people in order to keep power and wealth under their control.