Pope Benedict warned that when people forget God they risk falling under the influence of modern forms of idolatry, such as totalitarianism or nihilism.
The pope used the Old Testament story of the prophet Elijah to draw attention to the perils of idolatry in contemporary times.
In his talk at the June 15 audience in St. Peter's Square, the pope explained the story of how Elijah, alarmed at the spread of idol worship and syncretism in the Israel of the ninth century B.C., told his people they had to choose between God and the idol Baal.
In response, God sent down a consuming fire to reveal his presence and saving power, the pope said.
Pope Benedict said the story provided a valid lens for examining the 20th century.
"When God disappears, man falls into the slavery of idolatry, as we saw in our own time with totalitarian regimes" as well as various forms of nihilism "which make man dependent on the idolatry which enslaves him," he said.
In the story of Elijah, he said, God sends down fire which appears destructive but is rather "the fire of love which burns, transforms, purifies."