I have never been much of a math guy, but sometimes you have to see the numbers written on the walls.

For example, what essential thread runs through the following religion-beat stories? I am not arguing that this math hook is the only factor at play in these stories, but that this X-factor is a key piece in these puzzles.

* Nationwide, the Catholic church has been forced to close many of its parishes, especially in urban areas, along with their schools -- due to falling numbers in pews and desks.

* The Southern Baptist Convention has experienced a consistent, even if relatively small, decline in membership numbers. Baptisms have continued to decline. Meanwhile, the denomination's work with Latinos and African-Americans provides a crucial boost.

* Christian colleges, like their secular counterpart, now face increasing challenges in enrollment -- especially with the post-Millennial generation "cliff" looming ahead.

* Mormon numbers continue to rise. Same song, with new verses.

* Liberal Protestant churches continue a multi-decade demographic implosion, leaving a majority of congregations smaller, older and often (even with endowments from previous generations) swimming in red ink. The radical decline in the old mainline leaves a giant gap in American culture that provides an opening for evangelicals to grab the cultural spotlight.

* Jewish congregations, schools and social institutions face declining numbers, especially when it comes to finding families with children -- the link to the future.

* Greek Orthodox churches in North America face a shortage of priests who are, well, Greek and Greek-speaking. Many parishes (some tense about this) now have convert or Slavic priests.

* Conservative denominations -- think Missouri-Synod Lutherans, for example -- face falling enrollments in some of their elementary, middle and high schools, especially older schools far from suburbs.

* Home-schooling families continue to wield an increasing amount of power in evangelical circles.

I could go on and on with this. However, there is one other story linked to this issue that recently drew major coverage -- sort of -- in The New York Times and was the subject of my "Crossroads" podcast chat this week with host Todd Wilken (click here to tune that in).

Can anyone guess the topic?

Right, right, it was that piece on the ongoing crisis to recruit more priests for the Catholic Church. After lots of fascinating information on why two Michigan towns were producing an unusual number of priests, the Times team made one reference to the featured family having nine children.

Might the larger families, the higher birth rate, have something to do with the region's wealth of religious vocations? As I said the other day, demographics is destiny and so is doctrine.

Many, many religion stories today -- if you dig deep enough -- are complicated by realities linked to birth-rate issues, especially when that life-and-death number falls below 2.1 or thereabouts.

What is the link between higher birth rates and intense religious faith, if there is one? What is the birth rate today for liberal Protestants in America? How about suburban evangelicals? Mormons? Conservative Lutherans? And, yes, what is the reality today among urban and suburban Catholics?

Like I said the other day:

Parents are much more likely to consider encouraging their sons and daughters to serve the church when, well, there are more of them. If Catholic parents have one son, will they encourage the priesthood? One daughter?

The Times team sails right past this issue, which raises all kinds of questions about Catholic life and teachings, starting, of course, with artificial contraception. Why?

One more time, here is a flashback to 2002 and my interview with the Father Donald B. Cozzens, former vicar for clergy in Cleveland and then rector of a graduate seminary in Ohio. He is a well known and much-quoted Catholic progressive.

This attitude shift is especially significant when combined with a major statistical change in Catholic life. In the past, when large families were the norm, it was a matter of pride to have a son enter religious life. But what if most Catholic families contain only one son?

“When it has become normal to have two children or less, you are not going to find many parents who are encouraging a son — especially an only son — to become a priest,” said Cozzens. “They want him to get married, to have grandchildren and carry on the family name. ...

“So there are fewer sons and there are more mothers who are asking hard questions.”

This is how the birth-rate issue affects one major story.

What about the others? Do the math.

Enjoy the podcast.