The world's bishops, priests and deacons need people's prayers and encouragement to continually deepen their relationship with Jesus and serve their community with love, Pope Francis said.
A minister of God who does not nourish his love for Christ, his church and his flock "inevitably ends up losing sight and an authentic sense of his service and the joy that comes from a deep communion with Jesus," he said.
"Priests, bishops, deacons must care for the Lord's flock with love, and if they don't do it with love, they're unnecessary," he said Wednesday during his weekly general audience in St. Peter's Square.
The pope returned to a series of audience talks on the sacraments, focusing on the sacrament of holy orders.
Like the sacrament of marriage, the sacrament of pastoral ministry is a special way to follow Christ, give the gift of love and build up his church, he told the estimated 80,000 people in the square.
Jesus told his apostles to care for his sheep with the power of the Holy Spirit, not their own human efforts, and to do so "according to his heart," that is, with the same love Jesus had for others.
A pastoral minister "dedicates his whole being to his community and loves it with his whole heart: It is his family," Pope Francis said.
Those who are ordained become leaders of the Christian community, but, for Jesus, leadership is "offering your authority as service," the pope said.
A priest or "a bishop who isn't at the service of the community does no good," he said.
The pope said it is important to constantly renew and nourish the grace and joy of ordination through prayer, daily celebration of the Eucharist, penance, going to confession regularly and listening to the word of God, "which is our daily bread."
Bishops, priests or deacons who do not do these things diligently throughout life "lose communion with Jesus and they become mediocre, which is not good for the church," the pope said.
"That's why we have to help bishops and priests" to get closer to God with prayer and the sacraments and to help them to become more holy.
In various languages, the pope asked people to pray for the church's ministers so that they may be more holy, generous, authentic and merciful and especially to pray for those who are "most in need of our prayers" -- those who are experiencing difficulties or feeling discouraged.
The pope also urged young men to listen carefully to God's call to pursue a religious vocation.
After all, how do people become priests, the pope asked. "Where are they selling the admission tickets?"
"It's not something that's sold," he said: God makes the first move, calling the individual, asking him to become a priest.
So if any young men have felt in their hearts the desire "to spend one's whole life in service, to catechize, baptize, confess, celebrate the Eucharist, to heal the sick," it is God who planted that seed, which then needs prayer and care so that it may "grow and give fruit to the whole church."
At the end of the audience, a large delegation from Philadelphia, led by Archbishop Charles Chaput, met with the pope.
The delegation of government, religious and community leaders included Pennsylvania Gov. Tom Corbett and Philadelphia Mayor Michael Nutter. They were in Rome Monday through Wednesday to meet with Vatican officials to plan the World Meeting of Families in Philadelphia Sept. 22-27, 2015, and to urge the pope to attend.
The group hand-delivered letters and drawings for the pope from Pennsylvania students, and a Jewish couple gave the pope a dreidel, a wooden spinning top played during Hanukkah, the eight-day Jewish holiday known as the festival of lights.