A stately United Methodist church in our town, finally vacant, will be razed for a parking lot. A few remaining old-time members are saddened.

Actually, loss of once-thriving churches is common nowadays for Methodism and other parts of mainline Protestantism. They’ve suffered a half-century of relentless shrinkage.

Back in the 1960s, when U.S. Methodists merged with Evangelical United Brethren, the faith had 11 million adherents. At that time, the U.S. population was 180 million. Now the United Methodist Church has dropped to just 7 million American members, while the nation’s population almost doubled.

The same downsizing hit most other mainline branches. America’s two chief Presbyterian denominations (later merged) had 4.2 million members in the 1960s – but now the combined Presbyterian Church USA is down to 1.5 million. The Episcopal Church had 3.6 million in the 1960s, but only 1.8 million today. The Disciples of Christ fell from 1.9 million to 600,000.

When I came of age in 1950s, so-called mainline Protestantism – respected, “tall-steeple” churches with seminary-educated pastors – was the very essence of America. Catholicism and fundamentalism seemed like fringes.

But U.S. culture shifted. The mainline went into decline, while Catholics and evangelicals boomed. Megachurches featuring dynamic preachers blossomed. Pentecostalism, in which members speak in tongues, grew rapidly.

Then secularism – which soared in Europe and other democracies after World War II – hit America. Starting in the 1990s, the number of younger Americans who say their faith is “none” rose with surprising swiftness. Now, the Public Religion Research institute says “nones” have become America’s largest category at 25 percent, surpassing Catholics (21 percent) and white evangelicals (16 percent). Mainliners have fallen to around 15 percent, followed by Mormons at perhaps 7 percent or less.

Significantly, while Christianity declines in America, it is booming in southern, tropical, Third World nations. Pentecostalism has surged so much in the south that almost one-fourth of all the world’s Christians now follow this emotional faith.

At Easter, the director of the Billy Graham Center at Wheaton College wrote in The Washington Post that America’s mainline Protestants have “just 23 Easters left” if current decline rates continue.

Ed Stetzer said: “Now, less than one of 33 people you meet on the street regularly attends a mainline Protestant church. … Trend lines are showing a trajectory toward zero in both those who attend a mainline church regularly and those who identify with a mainline denomination 23 years from now. While the sky isn’t falling, the floor is dropping out.”

Of course, trends on charts rarely reach zero. But demographics show that U.S. religion has undergone enormous change. Not even prophecy believers can see what’s ahead.