My hypothesis

[Mister Agenda]

A religion must contain some kind of supernatural belief.  Most religions contain one or more deities, miracles/magic, and an essence of the self that persists through death.

Most anthropologists would disagree with your assessment.

If the list of oughts and ought nots of secular humanism constitute a religion, then what about law?  Is law also a religion?

Secular humanism doesn't constitute a religion (and you're misreading me if you think I said it does), nor does law. But religious humanism does, and it contains no supernatural belief.

By my reckoning, the majority of people with a PhD have no beliefs in deities, miracles/magic, or an essence of the self that persists through death. Therefore such people are without religion regardless of what they believe.

That's...interesting, I suppose.

If the standard of education reaches the point where a high school education becomes equivalent to today's PhD, and if you combine this with the trend that we already see of people leaving religion, then the extinction is inevitable.

When that happens, maybe the extinction of religion will be on the horizon. But I don't see why high education levels would induce people to leave religious humanism.

All we really need is for Islamic nations to modernize because in their current state there is virtually no selective pressure on Islam.

I think Islam is under intense selective pressure right now, but I'm not sure that what is being selected for is modernization.