Saddleback Church pastor Rick Warren gave the final keynote address of the World Meeting of Families conference in Philadelphia on Friday following a personal invitation from Pope Francis.

"Thank you for caring about the family," the Purpose Driven Life author told the crowd gathered at the conference, a week-long event sponsored by the Holy See's Pontifical Council for the Family. The theme of this year's conference was "Love Is Our Mission: The Family Fully Alive," emphasizing the impact of the love and life of families on society.

The megachurch pastor, who shared the stage with Cardinal Seán Patrick O'Malley, archbishop of Boston, repeated Pope Francis' warning that "Today families are being threatened. They're being threatened within and threatened without."

"In today's society, materialism is idolized, immorality is glamorized, truth is minimized, sin is normalized, divorce is rationalized, and abortion is legalized," Warren charged, the National Catholic Register reports. "In TV and movies, crime is legitimized, drug use is minimized, comedy is vulgarized, and sex is trivialized. In movies, the Bible is fictionalized, churches are satirized, God is marginalized, and Christians are demonized. The elderly are dehumanized, the sick are euthanized, the poor are victimized, the mentally ill are ostracized, immigrants are stigmatized, and children are tranquilized. In families around the world, our manners are uncivilized, speech is vulgarized, faith is secularized, and everything is commercialized."

Unfortunately, Christians are often disorganized and demoralized, their faith compartmentalized, and their witness compromised, Warren said. Thus, believers must "revitalize our worship, minimize our differences, mobilize our members, and evangelize the lost, and we need to re-energize our families."

Ultimately, joy-filled families base their love on the love of God and serve together. "Joy-filled families are filled with purpose. The goal of the family - Catholics call it the domestic church - is to help every person find their purpose," Warren said.

We're called to serve God, and God told us how to do that: by serving each other. The family, he says, "is a launch pad for ministry."

Warren revealed that as a teen, he was inspired by the late Catholic Bishop Fulton Sheen. The pastor recounted a story Sheen once told about his visit to a place where leprosy-affected people lived. The bishop bent over to speak to a man and his cross fell into the man's open wound. Sheen said the Holy Spirit filled him with an intense feeling of love for that man, and he took up the cross from the wound.

"I thought that was the finest definition of Christian living I'd ever heard," Warren said. "The whole business of life is to go out in the sores of life, where people are living and dying and suffering and pick up the cross. That is our ministry, and that is our service."

As reported by the Gospel Herald, Warren announced the Pope had personally invited him to speak at the popular event earlier in September: "I'm not a Catholic, and we have many differences with Catholics. But they love the Lord and we have much in common with that - we believe in the Bible, and the Trinity, and in Jesus and the resurrection," he said.

In the past, Warren has called on non-Catholic Christians to join with Pope Francis and the Catholic Church in pursuit of common goals, such as the sanctity of life and the sanctity of marriage.

In November, the pastor joined the leader of the Roman Catholic Church and 30 other global religious leaders for an interfaith Vatican conference on marriage and family, where he spoke on the "Biblical Meaning of Marriage."

"It's great to be with leaders from different streams of Christianity from all over the world," Warren said at the time. "Although we have some differences, we all love Jesus Christ and we all want marriage and families to be healthy and strong."