Living so close to the United States, it is impossible for Canadians not to be inundated by U.S. news — and often impacted by it, too. As one of our former prime ministers put it, it’s like sleeping with an elephant; we always have to wary for when it twitches or rolls over.

This is why we pay so much attention to what happens in the U.S., including in the area of religion. Which is why I am interested in a new book by Robert P. Jones, The End of White Christian America.

In it, Jones writes about the decline of mainline churches in the U.S. Fall­ing numbers, he says, are less about liberal doctrine and more about powerful demographic changes. Younger people today are simply less interested in religion.

Looking at the numbers, Jones says the proportion of Americans who are white mainline Protestants and white evangelicals today is 32 percent, down from 51 percent in 1993.

The reason for this change? More and more Americans are leaving organized religion, with 20 percent today considering themselves religiously unaffiliated.

Many of the unaffiliated are young adults, who are less than half as likely as seniors to identify with a church. This rejection of organized religion by youth, Jones says, is a “major force of change in the religious landscape.”

Looking ahead, “there’s no sign that this pattern will fade anytime soon,” he says. “By 2051, if current trends continue, religiously unaffiliated Americans could comprise as large a percentage of the population as Protestants.”

For a long time, the inability to retain youth was mostly a mainline church problem. But then, in 2008, evangelical numbers in the U.S. started to drop, too. Today 18 percent of Americans say they are evangelicals, down from 22 percent in 1988.

Jones says this evangelical decline is actually sharper and steeper than what happened to the mainline churches in the U.S. years earlier.

A comparison of the current affiliation patterns of the oldest and youngest Americans, says Jones, “reveals that white evangelicals have actually lost more ground than white mainline Protestants across current generations.”

For Jones, “these numbers point to one undeniable conclusion: white Protestant Christians —both mainline and evangelical — are aging and quickly losing ground as a proportion of the population.”

These changes in the U.S. mirror what is happening in Canada to Catholics and mainline denominations. From 1971 to 2011, the percentage of Canadians who identify as Catholic dropped from 47 percent to 39 percent, while the share that identified as Protestant fell even more steeply, from 41 percent to 27 percent. During that same time frame, the number of religiously unaffiliated grew from 5 percent to 24 percent.

Evangelicals in Canada are holding their own. But if what is happening in the U.S. is any indication, that trend may start being felt here soon, too.

Of course, there are still a lot of people who are serious about their Christian faith in the U.S. and Canada. Even with the changes, it would be foolish to suggest that organized Christianity is not still a powerful force in both countries.

But something profound is taking place. And we don’t yet fully know how it will affect the church and its institutions on both sides of the border.

John Longhurst, of Winnipeg, Man., is director of resources and public engagement at Canadian Foodgrains Bank.