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.
Benedict stressed that the state alone is responsible for creating that just society, not the church. "As a political task, this cannot be the church's immediate responsibility," he said.
However, he said the church wants to be involved in politics by helping "form consciences in political life and stimulate greater insight into the authentic requirements of justice as well as greater readiness to act accordingly, even when this might involve conflict with situations of personal interest."
He said the church was "duty-bound" to offer such a contribution, and that the lay faithful, who are citizens of the state, are duty-bound to carry it out through works of charity.
While stressing that the church has no direct political role, he does offer a prescription for what the state should do.
"We do not need a state which regulates and controls everything, but a state which, in accordance with the principle of subsidiary, generously acknowledges and supports initiatives arising from the different social forces and combines spontaneity with closeness to those in need," he wrote.
The text is divided into two parts: Part I explores what Benedict calls the "unity of love," in which he explains the two concepts of love found in the word "eros," love between man and woman, and the Greek concept of love in the world "agape," unconditional love, and how they are united in God's love and marriage between man and woman.
Part II takes that theological concept into concrete terms, which he said is found in the church's charitable activities, where the love of one's neighbor is put into practice.
Benedict began writing the encyclical in September, while on vacation at the papal summer retreat in Castel Gandolfo, papal spokesman Joaquin Navarro-Valls said.
He consulted others after it was written, including Archbishop Joseph Levada, an American who succeeded Benedict as prefect of the Congregation for the Doctrine of the Faith.
Levada said he didn't think it was at all unusual for such a great theologian to ask the opinions of others about his text. Nevertheless, he acknowledged he was "a bit surprised, also because I'm a bit new at this job."