Attempts to create a just world without God will fail, Pope Benedict XVI said yesterday in his second encyclical.

It is God who calls humans to rise above their selfishness and who sustains them when they suffer for doing the right thing, he wrote in "Saved in Hope." His examination of hope repeats his familiar themes concerning aggressive forms of secularism that relegate faith to, at best, a private hobby.

"We need the greater and lesser hopes that keep us going day by day. But these are not enough without the great hope which must surpass everything else. This great hope can only be God," he wrote.

"His kingdom is not an imaginary hereafter, situated in a future that will never arrive; his kingdom is present wherever he is loved and wherever his love reaches us."

His first encyclical was on love which, with hope and faith, is one of the three "theological virtues" in the New Testament.

"He is obviously working on a trilogy," said J. Peter Pham, a former Vatican official now teaching at James Madison University. "It will be the culmination of a theological vision that he has spent his entire life working on."

In Pittsburgh, auxiliary Bishop Paul Bradley responded for Bishop David Zubik, who was en route from Rome.

"It is hope that the world seems to lack today. True hope is based on God's unconditional love and justice," he said.

The first parts make arguments that most Christians could assent to but is written in the academic style of a German theology professor -- which this pope once was -- lecturing his graduate students. The last quarter is more readable, even poetic, but distinctively Catholic. It describes purgatory and ends with a prayer to Mary.

The Rev. Donald McCoid, chief ecumenical officer of the Evangelical Lutheran Church in America, said the pope showed ecumenical sensitivity.

"It gives us encouragement and hope that, indeed, we need to offer something to the world. Here is a word we can share," he said.

The encyclical describes atheism as a moral enterprise that erred in blaming the world's woes on God rather than on human sinfulness. He alludes to, but does not name, the massacres of millions under atheistic regimes such as Stalin's Soviet Union, Mao's China and Pol Pot's Cambodia.

"The atheism of the 19th and 20th centuries is ... a protest against the injustices of the world and of world history. A world marked by so much injustice, innocent suffering and cynicism of power cannot be the world of a good God," he wrote.

"If in the face of this world's suffering, protest against God is understandable, the claim that humanity can and must do what no God actually does or is able to do is both presumptuous and intrinsically false. It is no accident that this idea has led to the greatest forms of cruelty and violations of justice. ... A world which has to create its own justice is a world without hope."

Because he writes of ultimate hope, he writes of heaven, hell, purgatory and final judgment. He views longing for justice as evidence that people believe that those who have caused suffering must answer to a higher authority.

"To protest against God in the name of justice is not helpful. A world without God is a world without hope. ... The image of the Last Judgement is not primarily an image of terror but an image of hope," he wrote.

A running theme is that Christian faith cannot be lived in isolation, but requires the believer to offer love and hope to the wider community. This continues into eternity, he writes. Those in heaven pray for those on earth, and those on earth pray for the dead awaiting judgment to come to a transforming realization of God's love.

The latter is his description of purgatory. Nicholas Cafardi, a canon lawyer who teaches at Duquesne Law School and writes on the Catholic Church, said he thought it broke new ground.

"I had never heard [purgatory] as he described it, as this personal encounter with Christ at the end of your life, which at the same time burns you, transforms you and frees you. It's beautiful imagery," he said.

The pope says that although it's important to alleviate suffering, the Christian faith is not a political program. This echoes his critique decades ago of liberation theology, which was an effort to meld Christianity with Marxist social theory.

He treats Marxism as a well-intended movement that turned destructive because it denied God and the human capacity for evil. He critiques contemporary Christianity as too individualistic but regards this as an outgrowth of secular movements that rejected Christianity as a social force.

Marx "forgot that man always remains man. He forgot man and he forgot man's freedom. He forgot that freedom always remains also freedom for evil. He thought that once the economy had been put right, everything would automatically be put right," he wrote.

"We have all witnessed the way in which progress, in the wrong hands, can become and has indeed become a terrifying progress in evil."