Benedict began writing his personal meditation on Jesus Christ's teachings, entitled "Jesus of Nazareth," in 2003 when he was still Cardinal Joseph Ratzinger. He stressed that the book is an expression of his "personal search for the face of the Lord" and is by no means official Catholic Church doctrine.
"Everyone is free, then, to contradict me," he wrote.
Benedict - a prolific and well-known theologian well before he became pope - thoroughly examined the Gospel accounts of Jesus' public ministry to arrive at the foundation of the Christian faith: that Jesus is God.
Benedict said the fundamental question he is exploring in the book is what Jesus did.
"What did Jesus truly bring, if he didn't bring peace to the world, well-being for all and a better world? What did he bring?
"The answer is very simple: God. He brought God."
The 448-page book is due in bookstores in German, Italian and Polish on Monday, Benedict's 80th birthday. The English edition is due for release May 15 and translations are planned for 16 other languages.
The book is the first of two volumes: Rizzoli, the Italian publisher, said Benedict is expected to write a second volume exploring the birth of Christ, his crucifixion and resurrection.
"Jesus of Nazareth" covers several key points of Jesus' public life and ministry. An entire chapter is devoted to his baptism, another to the prayer Jesus taught the faithful, the Lord's Prayer, and another to Jesus' Sermon on the Mount, praising the poor, the meek and the hungry in the "Beatitudes."
"Confronted with the abuse of economic power, with the cruelty of capitalism that degrades man into merchandise, we have begun to see more clearly the dangers of wealth and we understand in a new way what Jesus intended in warning us about wealth."
In another chapter on the key Biblical parable, the Good Samaritan, Benedict decries how the wealthy have "plundered" Africa and the Third World both materially and spiritually through colonialism.
"Instead of giving them their God, the God that is close to us in Christ, and welcome from their traditions all that is dear and great ... we brought them the cynicism of a world without God, in which only power and profit matters," he wrote.
He criticized the lifestyles of the wealthy, citing "victims of drugs, of human trafficking, of sexual tourism, people destroyed on the inside, who are empty despite the abundance of their material goods."
Cardinal Christoph Schoenborn, the archbishop of Vienna and a friend of the pope's, told a Vatican presentation of the book on Friday that Benedict was seeking to portray Jesus as he was historically.
Despite the social justice tone of many of Jesus' teachings, however, Schoenborn said it would be wrong to call him a "social reformer."
He noted Benedict's tough stance on liberation theology - the theology of salvation as liberation from injustice - when he was prefect at the Vatican's Congregation for the Doctrine of the Faith. During his two-decade tenure as prefect, Ratzinger worked to cripple support for "liberation theology;" some versions of the movement, which is especially popular in Latin America, are at variance with church teaching because they view Christ as a mere social liberator. "The innumerable fanciful images of Jesus as a revolutionary, as a moderate social reformer, as the secret lover of Mary Magdalene, etc ... can be calmly deposited in the ossuary of history," Schoenborn said. AP-CS-04-13-07 1229EDT