At his final celebration in the United States before departing for Rome, Pope Francis told approximately one million people who attended Mass outdoors in Philadelphia Sunday that the simple daily acts of love expressed by family members to each other are what nurture both life and faith.

Having already warned at the World Meeting of Families—the primary event that called him to the United States—that marriage has been distorted to the extent that it is no longer representative of the Christian sacrament of matrimony, Pope Francis focused during his farewell homily on what he called “the gospel of the family” and how families must not only nurture the physical life of their members, but also their spiritual life as well.

“[L]ike happiness, holiness is always tied to little gestures,” the Pope said in his homily. “These little gestures are those we learn at home, in the family; they get lost amid all the other things we do, yet they do make each day different.”

Pope Francis continued:

They are the quiet things done by mothers and grandmothers, by fathers and grandfathers, by children. They are little signs of tenderness, affection, and compassion. Like the warm supper we look forward to at night, the early lunch awaiting someone who gets up early to go to work. Homely gestures. Like a blessing before we go to bed, or a hug after we return from a hard day’s work. Love is shown by little things, by attention to small daily signs which make us feel at home. Faith grows when it is lived and shaped by love. That is why our families, our homes, are true domestic churches. They are the right place for faith to become life, and life to become faith.

The Pope’s words hearken back to those of the Second Vatican Council which defined the family as a “domestic church,” a small-scale version of the universal Church.

On the previous Saturday evening during a festival of prayer, music, and art, the Pope spoke about some of the difficulties inherent in everyday family life as well. He was animated as he joked knowingly during his address, given in his native Spanish, “Families quarrel… sometimes plates can fly and children give headaches.”

“I won’t speak about mothers-in-law,” he laughed.

Pope Francis spoke very seriously earlier on Sunday to U.S. bishops about the challenges to traditional family life, even referring to the recent Supreme Court decision legalizing same-sex marriage:

Needless to say, our understanding, shaped by the interplay of ecclesial faith and the conjugal experience of sacramental grace, must not lead us to disregard the unprecedented changes taking place in contemporary society, with their social, cultural – and now juridical – effects on family bonds. These changes affect all of us, believers and non-believers alike. Christians are not “immune” to the changes of their times. This concrete world, with all its many problems and possibilities, is where we must live, believe, and proclaim.

The Pope went on to liken our contemporary culture both to a “supermarket” and a ‘huge multicultural showcase” in which “the most important thing nowadays seems to be follow the latest trend or activity.” He called upon the bishops to extend themselves to young people, encouraging them to forgo a life focused solely on themselves, and to make a choice instead for marriage and family.

“We need to invest our energies, not so much in rehearsing the problems of the world around us and the merits of Christianity, but in extending a sincere invitation to young people to be brave and to opt for marriage and the family,” he urged the bishops. “A pastor must show that the ‘Gospel of the family’ is truly ‘good news’ in a world where self-concern seems to reign supreme!”

“We are not speaking about some romantic dream: the perseverance which is called for in having a family and raising it transforms the world and human history,” he said.

Even as he addressed the importance of family life in the development of faith, Pope Francis also spoke to the bishops about the value of celibacy in the priesthood.

“A good pastor renounces the love of a family precisely in order to focus all his energies, and the grace of his particular vocation, on the evangelical blessing of the love of men and women who carry forward God’s plan of creation,” he said. “This total surrender to God’s agape is certainly not a vocation lacking in tenderness and affection! We need but look to Jesus to understand this (cf. Mt 19:12).”

During his final Mass in the United States, Pope Francis remarked on the great numbers of families present at the 8th World Meeting of Families.

“This is itself something prophetic, a kind of miracle in today’s world,” the Pope said. “Would that we could all be prophets! Would that all of us could be open to miracles of love for the sake of all the families of the world, and thus overcome the scandal of a narrow, petty love, closed in on itself, impatient of others!”

Veering off his prepared homily for a moment, Pope Francis suggested the kind of reflection that might help families to measure their love for each other.

“In my house do people yell, or do you speak with affection and kindness?” he asked. “This is a good way to measure our love. How nice it would be if everywhere – and beyond our borders – we could appreciate and encourage this prophecy and this miracle.”