Speaking to the members of the tribunal of the Roman Rota, Benedict said "lack of faith" on the part of the spouses can affect the validity of a marriage.
A lack of faith in God can damage marriage, even to the point of affecting its validity, Pope Benedict XVI said.
"Faith in God, sustained by divine grace, is therefore a very important element for living in mutual dedication and conjugal fidelity," he said.
The pope said he was not suggesting there was a simple, automatic link "between the lack of faith and the invalidity of marriage."
Diplomatic relations between the Vatican and Vietnam were strengthened in January, officials said, when Pope Benedict XVI met Nguyen Phu Trong, marking the first time a pope had met with the general secretary of the nation's Communist Party.
Trong, who has been general secretary of the party since 2011, was accompanied by an 11-person delegation of other high-level party and government officials. The Vatican was one of a number of stops the delegation had planned in Europe.
The Vatican on Thursday defended the pope's choice to open a Twitter account, even if it exposes him to insults and online abuse.
"Twitter is a secular reality ... but we prefer to be present rather than stay away from something just to avoid a risk," said Archbishop Claudio Maria Celli, head of the Vatican's department for social communications, during the launch of the annual papal message for World Communications Day.
Pope Benedict XVI opened his Twitter handle @Pontifex on Dec. 3. It has since gathered more than 2.5 million followers in nine languages, including Latin.
The Catholic church has never encouraged anyone to use ivory for religious devotional objects and, in fact, teaches that animals must be treated with respect, the Vatican spokesman said in a letter to "friends of the elephants."
Jesuit Fr. Federico Lombardi, responding to questions posed in an online National Geographic editorial, said, "thinking that there is an important ivory trafficking center to uproot here (in the Vatican) in order to save African elephants makes no sense."
The Society of St. Pius X will have a future only if it stops publicly criticizing the teaching of the pope, said the Vatican official responsible for relations with traditionalist Catholics.
Pope Benedict XVI named Msgr. Eamon Martin as coadjutor archbishop of Armagh, Northern Ireland, making him the designated successor to Cardinal Sean Brady as the head of the Catholic church in Ireland.
The Vatican announced the appointment Friday.
After serving as vicar general of the Diocese of Derry, Northern Ireland, last year Martin became its diocesan administrator upon the retirement of Bishop Seamus Hegarty.
Pope Benedict XVI gave new assignments in mid-January to two U.S. archbishops serving as Vatican ambassadors.
Archbishop Joseph Marino, a native of Birmingham, Ala., who will be 60 on Jan. 23, was named the Vatican's first nuncio to Malaysia, as well as nuncio to East Timor and apostolic delegate in Brunei.
Archbishop Charles Balvo, a 61-year-old native of Brooklyn, was named nuncio to Kenya, as well as observer at the U.N. Environment Program and its Agency for Human Settlements, both based in Nairobi.
The Vatican on Wednesday criticized a ruling from the European Court of Human Rights that affirms employers' right to limit the expression of religious beliefs in the workplace when it conflicts with equality laws.
In an interview with Vatican Radio, Archbishop Dominique Mamberti, the Vatican's foreign minister, said that on "morally controversial subjects, such as abortion or homosexuality," people have the right to defend their freedom of conscience.
In an effort to flex its moral muscle in the professional sports arena, the Vatican has invited top-tier Christian athletes Tim Tebow and Jeremy Lin to help bring ethical values back to a scandal-ridden world of sports.
The Pontifical Council for Culture is planning to host an international conference on re-instilling values in sports this spring, inviting representatives from top world governing bodies like FIFA (the International Federation of Association Football), the International Cycling Union and the Italian National Olympic Committee.