Most Rev. J. Peter Sartain is being installed as Seattle's fifth Roman Catholic archbishop at St. James Cathedral.

The former bishop of Joliet, Ill., officially became the new spiritual leader of nearly 1 million Catholics across Western Washington, making him the youngest Catholic archbishop in the United States.

Considered politically moderate, deeply spiritual and down to earth, the Most Rev. J. Peter Sartain, 58, was installed as the new archbishop of the Seattle Archdiocese at a Mass Wednesday afternoon at St. James Cathedral.

Among those in attendance were three cardinals — Francis George of Chicago, Roger Mahony of Los Angeles, and Donald Wuerl of Washington, D.C., who served as auxiliary bishop in Seattle for a time in the 1980s — and 20 bishops and archbishops.

During the Mass, a representative of Archbishop Pietro Sambi, the Vatican’s ambassador to the United States, and Sartain’s predecessor, the Most Rev. Alex Brunett, walked Sartain to the bishop’s chair.

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Brunett then handed Sartain his crosier — a bishop’s staff that symbolizes his authority. Brunett wanted to give Sartain the 14-pound crosier to remind Sartain of the weight of the office, said Seattle Archdiocese spokesman Greg Magnoni.

It was at that point that Sartain formally became Seattle’s archbishop.

Brunett, who is retiring, submitted his resignation letter to the Vatican last year when he turned 75. The Vatican named Sartain as his successor in September.

Hours before the Mass began, the streets around St. James were bustling, with priests in clerical garb, seminarians in dark suits, and lay Catholics — some in colorful regalia — milling around the cathedral.

Kyle Manglona, a 20-year-old seminarian, came with several dozen of his fellow students from their seminary in Spokane.

“It’s a new shepherd. It’s an exciting day,” Manglona said, adding that the church has been having events like this for 2,000 years. “It shows the historical continuity of the church and that the church is alive in today’s world.”

Pia de Solenni, a lay Catholic who attends Christ the King church in North Seattle, came to take part in the honor guard as a member of the Order of Malta, a Catholic organization that serves the sick and the poor.

“He’s come to serve us, and we want to serve him,” she said. A bishop, she said, “is the chief pastor here. It’s a very strong bond that Catholics have with their bishop.”

Sartain served as bishop in Joliet for four years, and before that was bishop of the Diocese in Little Rock, Ark.

As archbishop in Seattle, he will oversee the largest of this state’s three Catholic dioceses, with 178 parishes and missions and a large social-services operation.

Unlike some other dioceses, Seattle’s has has remained relatively stable financially under Brunett’s nearly 13-year tenure, though the recession has left it with little financial cushion.

Sartain is also coming into an archdiocese that is politically, economically and ethnically diverse — about 1 in 4 Catholics is Hispanic and many others are from Asian countries.

And while many Catholics here favor liberal causes such as gay marriage and abortion rights, others hold to traditional teachings against those practices. Similar divides exist over such church policies as mandatory celibacy for priests and banning women from the priesthood.

Sartain is also stepping into a Northwest culture that’s strongly secular and so — outside of his role within the church — he may not have as much sway as in other parts of the country.

And he also will have to manage the the church’s continuing clergy sexual-abuse crisis. Members of a sex-abuse victims’ group, Survivors Network of those Abused by Priests, planned to demonstrate outside St. James, passing out leaftlets urging Catholics to pressure Sartain to disclose details about a priest he ordained in the Joliet Diocese last year. That priest had been caught some months earlier with pornography on his computer.

Earlier this year, after the priest was accused of sexually abusing a boy, Sartain removed him from his position and publicly apologized to the boy and his family.

Sartain was born in Memphis in 1952, later earning bachelor’s degrees from St. Meinrad College in Indiana and the Pontifical University of St. Thomas in Rome. He holds an advanced degree in sacred theology from the Pontifical Athenaeum San Anselmo in Rome.

He was named bishop of the Diocese of Joliet, Ill., in 2006 and before that was bishop of the Diocese of Little Rock, Ark.

There, Sartain learned Spanish to communicate with Hispanic Catholics and is also credited with helping bring young men into the priesthood.