In the long-awaited document "God is Love," Benedict explores the relationship between God's love for mankind and the church's works of charity, saying the two are intrinsically linked and the foundation of the Christian faith.
The 71-page encyclical, eagerly watched for clues about Benedict's major concerns, has characterized his early pontificate as one in which he sought to return to the basics of Christianity with a relatively uncontroversial meditation on love and the need for greater works of charity in an unjust world.
Even Vatican officials have expressed some surprise at the topic, considering Benedict was the Vatican's chief doctrinal watchdog and could easily have delved into a more problematic issue such as bioethics in his first authoritative text.
In the encyclical, Benedict said the church's work caring for widows, the sick and orphans was as much a part of its mission as celebrating the sacraments and spreading the Gospels. However, he stressed that the church's charity workers must never use their work to proselytize or push a particular political ideology.
"Love is free; it is not practiced as a way of achieving other ends," he wrote.
"Those who practice charity in the church's name will never seek to impose the church's faith upon others. They realize that a pure and generous love is the best witness to the God in whom we believe and by whom we are driven to love."
However, he said that the church's charity workers must be inspired by faith and love in God and not just a desire to make the world a better place, a point emphasized during a news conference by Archbishop Josef Cordes, who heads the Vatican's charity organization Cor Unum.
"Without a solid theological foundation, the big church agencies could be threatened in practice by disassociating themselves from the church and relaxing their links with bishops," Cordes said. "They could prefer to identify themselves as non-governmental organizations," like the Red Cross or the United Nations.
In the encyclical, Benedict rejected the criticism of charity found in Marxist thought, which holds that charity is merely an excuse by the rich to keep the poor in their place when the rich should be working for a more just society.
While the Marxist model, in which the state tries to provide for every social need, did respond to the plight of the poor faster than even the church did during the Industrial Revolution, it was a failed experiment because it couldn't respond to every human need, he wrote.
Even in the most just societies, charity will always be necessary, he said.
"There will always be suffering which cries out for consolation and help. There will always be loneliness. There will always be situations of material need where help in the form of concrete love of neighbor is indispensable," he said.