Rome (CNN) -- Thousands of Catholics waving flags from around the world packed St. Peter's Square on Sunday to hear Pope Francis deliver his inaugural Angelus.
The new pontiff gave his Angelus, or noon blessing, from the papal apartment window, speaking to more than 200,000 worshippers in the square four days after his election as pope.
"Dear brothers and sisters, good morning," he said in Italian, drawing cheers from the crowd.
During the 15-minute address, he focused on forgiveness.
"Never forget this: The Lord never tires of forgiving us," he said. "Have you thought about the patience that God has with each of us?"
He made the historic address after celebrating Mass at Sant'Anna parish in Vatican City earlier Sunday.
In a rare move for a pope, Francis spontaneously walked out from Vatican territory to greet cheering well-wishers outside Sant'Anna Gate.
"Francesco, Francesco!" the crowd chanted.
Also on Sunday, the pope sent out his first message from the papal Twitter account: "Dear friends, I thank you from my heart and I ask you to continue to pray for me. Pope Francis."
In his first week as pontiff, Francis has enjoyed global fanfare as the first Latin American pope and the first Jesuit pope in modern times.
The official Mass to inaugurate Francis as the bishop of Rome -- and leader of the world's 1.2 billion Roman Catholics -- will take place Tuesday.
A church 'for the poor'
The new pope explained his choice of the name Francis in a meeting with journalists Saturday and discussed how he wished for a church that was both poor and "for the poor."
Francis, who before he became pope was Cardinal Jorge Bergoglio, said a fellow cardinal from Brazil had told him "Don't forget the poor" as the votes stacked up in his favor.
"Right away, with regard to the poor, I thought of St. Francis of Assisi, then I thought of war," he told the assembled journalists. "Francis loved peace and that is how the name came to me."
He had also thought of St. Francis of Assisi's concern for the natural environment, he said, and how he was a "poor man, a simple man, as we would like a poor church, for the poor."
St. Francis of Assisi, who gave up his own wealth and prestige, is revered among Catholics for his work with the poor.
A blessing for all
The new pope concluded the meeting with press -- which did not include questions -- with a blessing for all the journalists present and their families.
Francis acknowledged that not all those present were Catholic, saying he gave them his blessing "knowing that you are of different religions, because all of you are children of God."
As a cardinal in Buenos Aires, he developed close relations with Argentina's Jewish community.
He wrote to the chief rabbi in Rome last week, saying he strongly hoped to "contribute to the progress of the relations that have existed between Jews and Catholics" since the Second Vatican Council in the 1960s, which redrew the church's relations with the modern world, "in a spirit of renewed collaboration."
Reforms to come?
In just his first few days as pope, Francis has prompted speculation that he may bring in wider changes.
While he decided the heads of the various Vatican offices will keep their jobs for now, he's not making any definitive appointments, the Vatican said Saturday.
CNN Vatican analyst John Allen, who's also a correspondent for the National Catholic Reporter, said this is the first clear signal that he may be serious about reform.
"It's customary for new popes to swiftly reconfirm the department heads who lose their positions when the previous pontificate ends, and then take his time about bringing in his team," Allen said.
"The fact that Francis has not followed that path may suggest that significant personnel moves will come sooner rather than later."
Francis wants "a certain period for reflection, prayer and dialogue before (making) any definitive nomination or confirmation," the Vatican statement said.
Questions about the past
The Vatican has sought to quell controversy over Francis' conduct during Argentina's so-called Dirty War, amid accusations that he could have done more to protect two Jesuit priests who were kidnapped.
In a news conference Friday, the Vatican rejected the allegations as defamatory and untrue.
"This was never a concrete or credible accusation in his regard. He was questioned by an Argentinian court as someone aware of the situation but never as a defendant. He has, in documented form, denied any accusations," said the Rev. Federico Lombardi, a Vatican spokesman.
"Instead, there have been many declarations demonstrating how much Bergoglio did to protect many persons at the time of the military dictatorship," he said.
A meeting on the pope's agenda Monday may be another sign that he's trying to put the past behind him. Argentine President Cristina Fernandez de Kirchner is scheduled to meet with Francis Monday afternoon.
As archbishop of Buenos Aires in 2010, Francis sharply criticized her government's push to legalize gay marriage, calling proposed legislation "a destructive attack on God's plan." With a front-page counterpunch, the president said the church possessed "attitudes reminiscent of medieval times and the Inquisition."
Some analysts thought Fernandez's lukewarm praise of Francis after he was elected to the papacy Wednesday signaled that old tensions were still simmering. But on Sunday, Argentina's state-run Telam news agency trumpeted Fernandez's arrival in Rome and said she would be the first head of state to meet with the Francis in his new role.
Meeting with Benedict XVI
Francis will meet with his predecessor, Pope Emeritus Benedict XVI, on Saturday, the Vatican said.
The meeting will take place at the papal summer residence, Castel Gandolfo, where Benedict has been staying since his historic resignation.
It comes amid concern in some quarters that the presence of a living former pope might lead to a conflict of interests or influence.
The Vatican has said that Benedict will not seek to interfere in the running of the church, but will focus on study and prayer.
Hada Messia reported from Rome, and Holly Yan wrote from Atlanta. CNN's Laura Smith-Spark, Karen Smith, Catherine E. Shoichet and Mariano Castillo also contributed to this report.