The Russian Orthodox Church was resurrected after the 1991 collapse of the Soviet Union, ending 70 years of often brutal Communist repression. The church seems only too happy to hitch its halting rebirth to Mr. Putin’s fortunes, hoping to attract more adherents. Although 80 percent of the 140 million Russians identify themselves as Russian Orthodox culturally, the number who actually attend church is tiny. The church says it is nearly 10 percent, but experts say it has long hovered around 3 percent.

Another reason for St. Sergius’s elevation is the current crisis in Ukraine.

The birth of the Russian Orthodox faith dates back to Vladimir the Great, grand prince of Kiev, and the mass baptisms performed at his behest there in 988, bringing Christianity to what then became Holy Rus.

But now that Russia and Ukraine are locked in a proxy war, the government and the church realize that the physical link to an important religious symbol is being severed, noted Geraldine Fagan, author of “Believing in Russia — Religious Policy After Communism.”

Because those roots — not to mention the relics of St. Vladimir himself — are in the territory of an estranged neighbor, Russia appears to be casting St. Sergius as his replacement, Ms. Fagan said.

In the late 14th century, aside from founding the first monastery, St. Sergius of Radonezh persuaded the Russian princes to stop their murderous, internecine fighting and concentrate on throwing off the Mongol yoke.

“St. Sergius was the beginning not just of Russian monasticism or the Russian spiritual tradition,” said Vladimir Legoyda, the head of the information department for the Holy Synod. “In many ways he is the source of Russia itself.”