With an inaugural homily urging respect for "God's creation", Pope
Francis on Tuesday subtly pressed a conservative Catholic message while
urgent challenges loom for the Church.The first Latin American pope has been heralded by supporters as a progressive, but scholars say he is unlikely to bend on Church doctrine -- and key moral issues were glaringly absent from his speech.
His predecessor Benedict XVI formally resigned because of old age, but some religious watchers say he buckled because of a bitter power struggle within the Church and a poisonous sexual abuse scandal -- concerns that Francis will have to address.
He will also be expected to speak out on issues such as the ordination of women, priest celibacy, abortion, euthanasia and gay marriage.
In an address influenced by the teachings of his namesake St Francis of Assisi, the 76-year-old Jesuit said he would "embrace with tender affection the whole of humanity, especially the poorest, the weakest, the least important".
He called on world leaders not to "allow omens of destruction and death to accompany the advance of this world", without referring to specific conflicts.
Instead, he urged the faithful to "protect all creation" and cited the Bible calling on Christians to embrace "the hungry, the thirsty, the stranger, the naked, the sick and those in prison".
"Discreetly, he referred to the dignity of all human life -- the vulnerable and people who are the most poor," said Robert McCabe, a priest from Ireland.
"He's raised the bar for every parish priest, he's raised the bar for every NGO, he's raised the bar for every religious leader and raised the bar for all the government leaders who are here present at St Peter's," he told AFP.
While his first speeches have emphasised the need for a simpler faith and social justice, Francis will soon have to move beyond generic statements and tackle the substance of the thorny issues facing the Church.
The new head of the Roman Catholic Church has been called on to rein in the unruly Curia, the Church's governing body, and deal with the fallout from the "Vatileaks" affair which last year saw Benedict's butler jailed for documents revealing intrigue in the Vatican.
"Amid so much darkness, we need to see the light of hope," said Francis, whose appointments over the coming weeks will be closely watched.
The Vatican may have apologised for child abuse by priests, but campaigners are calling for more to be done to bring suspects before the law or punish senior prelates who have covered up abuse.
There are calls for more transparency on the issue too in other parts of the world beyond just Europe and the United States, where virtually all the abuse scandals have originated.
As Buenos Aires archbishop Jorge Mario Bergoglio has been accused of failing to do enough to counter the scourge, but in a 2010 interview he stressed the importance of vetting seminarians for the priesthood.
"If a priest is a paedophile, he carries this perversion within him before being ordained," Bergoglio said in "The Jesuit" by Sergio Rubin and Francesca Ambrogetti.
As cardinal, Bergoglio was a fervent critic of the International Monetary Fund and unregulated market capitalism and has warned against globalisation -- a stance that could make him an important voice in Europe with its draconian austerity budgets.
While Francis has signalled he will pursue a more inclusive "collegial" style of leadership in an attempt to boost growing secularism in the West, he is against proposals to open up the clergy to women to combat dwindling priest numbers.
He is also against ending celibacy among priests or changing the role of women in the Church and is not expected to open discourse on divorced Catholics who are not allowed to take part fully in church services.
He has spoken out most strongly in the past against gay marriage, saying before it was legalised in Argentina in 2010: "Let's not be naive. This is not just a political struggle. It is destructive to God's plan."
In keeping with mainstream Catholic thought he also opposes abortion and has said unborn life is not some "tumour" that has to be removed.
He is also against all use of condoms, even to prevent AIDS. Benedict had suggested contraception could be used in rare cases to avoid disease but the Vatican quickly backed down from any hint of a doctrinal shift.
Francis famously opposes the Church meddling in politics -- but may be forced to tackle the sticky question as to his role in Argentina's "Dirty War".
Bergoglio was 40 when a military junta overthrew the government, and has been criticised for not being more outspoken in opposition to the regime and allegedly failing to protect two Jesuit priests kidnapped and tortured for five months.
The Vatican has vigorously denied the claims.
He said on Tuesday: "Tragically, in every period of history there are 'Herods' who plot death, wreak havoc, and mar the countenance of men and women."