...cenario Five

As culture continues to move toward a future of questioning and doubt, Christianity has to "develop a cultural practice of positive questioning, of active holy doubt, and a clear articulation of what is eternal and what is in flux," he notes.

That practice is likely to be constructed not by theologians, Kelly says, but by members of the worldwide church in a distributed social media context. "The wiki-church."

And that includes Muslims.

The Christian community is shrinking in Europe while the Islamic community continues to grow. And while Islam has turned radical and militant in other parts of the world, Kelly points to the millions of non-militant moderate Muslim communities.

"On many social issues moderate Islam and conservative Christianity agree," he contends. "They are both people of the book. They both honor many of the same prophets. They agree on many religious issues like prayer, sexuality, sin, and family.

"It is not impossible to imagine Muslims and Christians becoming allies in the inevitable culture wars of the future. It is no more impossible than imagining Christians and Jews would be allies a thousand years ago."

Kelly predicts 100 years from now, a conservative Christian-Islam alliance might be a serious global political force.