"To protect creation, to protect every man and every woman, to look upon them with tenderness and love is to open up a horizon of hope," he told between 150,000 and 200,000 people gathered under sunny skies in St. Peter's Square and the nearby streets.
With representatives of other Christian churches and communities, delegations from 132 countries, Jewish and Muslim leaders as well as Buddhists, Hindus, Sikhs and Jains present, Pope Francis preached the Gospel, but insisted the values it espouses are essentially human, "involving everyone."
While the rites and rituals of the inauguration of his ministry as Pope took place immediately before the Mass, the liturgy itself was a celebration of the feast of St. Joseph, patron of the universal Church and "also the name day of my venerable predecessor," Pope Benedict XVI, the former Joseph Ratzinger.
The retired pope was not present at the liturgy, but the crowds applauded enthusiastically when Pope Francis said, "We are close to him with our prayers, full of affection and gratitude."
The new Pope stood at a lectern to read his homily, sticking to the text he had prepared in advance. At times his voice was extremely soft and other times it was quite loud; he punctuated with clenched fists his remarks about the strength required to be tender and compassionate to others. (Read a complete transcript of the homily.)
"In the Gospels," he said, "St. Joseph appears as a strong and courageous man, a working man, yet in his heart we see great tenderness, which is not the virtue of the weak, but rather a sign of strength of spirit and a capacity for concern, for compassion, for genuine openness to others, for love.
"We must not be afraid of goodness, of tenderness," Pope Francis said.
The new Pope said exercising the role of protector as St. Joseph did means doing so "discreetly, humbly and silently, but with an unfailing presence and utter fidelity, even when he finds it hard to understand."
The Gospels present St. Joseph as a husband to Mary, "at her side in good times and bad," and as a father who watched over Jesus, worried about Him and taught Him a trade, the Pope said.
St. Joseph responded to his call to be a protector "by being constantly attentive to God, open to the signs of God's presence and receptive to God's plans, and not simply his own," the Pope said.
Fidelity to God's word and God's plan for individuals and for all of creation makes the difference, he said, calling on everyone to be sensitive and loving toward those in their care, especially toward children, the aged, the poor and the sick.
"In the end, everything has been entrusted to our protection, and all of us are responsible for it," he said. "Be protectors of God's gifts."
When people fail to respect creation, when they ignore "God's plan inscribed in nature," or when they treat each other with disrespect, he said, "the way is opened to destruction, and hearts are hardened."
"Tragically, in every period of history there are 'Herods' who plot death, wreak havoc and mar the countenance of men and women," he said.
Pope Francis asked the government leaders present and all those with responsibility in the field of economics, politics and social life to stand firm when destruction and death threaten human dignity, human life and the environment. He met with the heads of the government delegations after the Mass.
Caring for others, he said in his homily, must begin with watching over one's own heart, mind and actions, resisting "hatred, envy and pride" and emotions that can tear others down.
Pope Francis told the people he realized his new ministry included "a certain power," but it is the same power Jesus conferred on St. Peter, which was the "power of service" seen in Jesus' charge to St. Peter: "Feed my lambs. Feed my sheep."
"Let us never forget that authentic power is service and that the Pope, too, when exercising power, must enter ever more fully into that service which has its radiant culmination on the cross," he said.
"He must be inspired by the lowly, concrete and faithful service which marked St. Joseph and, like him, he must open his arms to protect all of God's people and embrace with tender affection the whole of humanity, especially the poorest, the weakest, the least important," Pope Francis said.
"Only those who serve with love are able to protect."