Book Club - God is Back #4 & #5 - Fall 2011

One of the most interesting chapters in God is Back is the chapter on the "The Bible versus the Koran." From p. 282:

[T]he plain fact is that the Islamic world is a long way behind the Christian one in its engagement with modernity. Islam is coming to a succession of epochal religious debates--particularly about the relationship between faith and authority--much later than Christianity. Christianity, particularly in its American version, has resolved those debates in a way that has rendered it well equipped to thrive along with modernity.

For this and other reasons, the authors see Christianity as still ahead in the competition between Christianity and Islam.

In prior posts on the blog, I have raised doubts about this conclusion. Definitely check out these earlier posts here and here to see my doubts. Stephen Prothero, in his 2010 book God is Not One: The Eight Rival Religions that Run the World--and Why their Differences Matter, gives the nod to Islam in terms of impact on society today:

The case for Christianity's preeminence is compelling. In the United States, the most powerful country in the world, Christianity is the religion par excellence. . . . Nonetheless, Islam is the Muhammed Ali of the world's religions. Statistically, it is second to Christianity, but its numbers are growing far more rapidly. . . . Numbers aside, Islam is the leader of the pack in terms of contemporary impact.

So which is it? Is Christianity winning the battle? Does Islam have the bigger impact? Is it possible to have both?