In a major document released on his 25th anniversary today, Pope John Paul issued an indictment of rich nations and said a "war of the powerful against the weak" seemed to be embroiling the world.
"In many areas the world resembles a powder-keg ready to explode and shower immense suffering upon the human family," he said in the 192-page booklet.
In it, he also appeared to criticise the US church over its paedophilia crisis, saying bishops have to move quickly to repair scandal and protect victims when clerics commit crimes.
He condemned wars of religion and reaffirmed the Roman Catholic Church's rule of celibacy for priests.
Pastores Greges(Shepherds of the Flock) tackles a wide array of issues that arose in a synod of the world's Roman Catholic bishops two years ago.
The document includes a heartfelt appeal for rich countries not to lord it over the wretched of the Earth.
"The war of the powerful against the weak has, today more than ever before, created profound divisions between rich and poor," he said. "The poor are legion!"
"Within an unjust economic system marked by significant structural inequities, the situation of the marginalised is daily becoming worse," he wrote. "Today, in many parts of the world, people are starving, while in other places there is opulence."
The Church's mission was to defend the downtrodden and oppressed "because if there is no hope for the poor, there will be no hope for anyone, not even for the so-called rich".
The pope, who signed the document at a brief ceremony in the Vatican's vast audience hall, said the primary victims of inequality today were the poor, the young, refugees and women.
In phrases applicable to the Middle East and parts of Asia, he condemned "the unacceptable exploitation of religion for violent purposes" and branded religious fundamentalism "a constant enemy of dialogue and peace".