In his first Mass in the United States, Pope Francis on Wednesday canonized a 18th-century Spanish missionary who spread Christianity across California but who also was controversial for overseeing the mistreatment of Native Americans who joined his flock.

A throng of worshipers celebrated the Rev. Junípero Serra’s elevation to sainthood — the first canonization on U.S. soil — during a late-afternoon Mass at the Basilica of the National Shrine of the Immaculate Conception in Northeast Washington.

“He was the embodiment of a church which goes forth, a church which sets out to bring everywhere the reconciling tenderness of God,” Francis said in his homily, which he delivered in his native Spanish on the steps leading to the basilica. “He learned how to bring to birth and nurture God’s life in the faces of everyone he met; he made them his brothers and sisters.”

The pope acknowledged Serra’s connection to Native Americans, though he did not address this ­controversial history, which has prompted some tribal groups to portray the missionary as a colonist who subjected their ancestors to coercive indoctrination.

Instead, the pope said, “Junípero sought to defend the dignity of the native community, to protect it from those who had mistreated and abused it. Mistreatment and wrongs which today still trouble us, especially because of the hurt they cause in the lives of many people.”

Pope Francis is greeted by a large crowd as he prepares to deliver a historic Canonization Mass during which he will make Junipero Serra a saint. (AP)

After the Mass, Francis met with a small group of Native Americans during a private reception.

Vatican officials have acknowledged in the past that Serra was fallible. But they have also said that his canonization is the result of the fact that he left his native land to deliver religious teachings to what was then considered the new world.

With the grandeur of the basilica as a backdrop, the service brimmed with historical significance as the first Hispanic pope canonized the first Hispanic saint with ties to the United States. Serra’s elevation allows the Vatican to highlight Hispanic influence over the Catholic Church. Latinos account for about 40 percent of the church’s U.S. followers.

In the United States, Serra’s historical significance is sufficient enough that the monk is among two Californians — Ronald Reagan is the other — who are represented with statues in the U.S. Capitol’s Statuary Hall.

A theologian in his native Majorca, Serra surrendered life as an academic to spread Gospel teachings, sailing from Spain to Mexico in 1749 and then serving penance by walking 250 miles from Veracruz to Mexico City.

Twenty years later, he established a network of missions along the California coast, marching north with Spanish conquistadors and helping to propel the area toward modernity.

Historians have credited Serra with seeking to immerse Native Americans in the Gospel. But he has also been criticized for subjecting Indians who joined his mission to flogging and forcing them to relinquish their religion, their culture, the way they dressed and how they ate.

In his homily, the pope urged Catholics to rejoice in their faith. Yet he also expressed concern about the “struggles of everyday life” and all that stands “in the way of this invitation to rejoice.”

“Our daily routine,” Francis said, “can often lead us to a kind of glum apathy which gradually becomes a habit, with a fatal consequence: Our hearts grow numb.”

“So we ought to ask ourselves,” he said, “ ‘What can we do to keep our heart from growing numb, and becoming anesthetized? How do we make the joy of the Gospel increase and take deeper root in our lives?’ ”

The pope cited Serra as an example of a missionary who fought to “keep his heart from growing numb, from being anesthetized.”

Quoting Serra’s favorite motto, “Siempre adelante!,” which means “Keep moving forward,” the pope said: “He kept moving forward, because the Lord was waiting. He kept going, because his brothers and sisters were waiting. He kept going forward to the end of his life.

“Today, like him,” the pope concluded, “may we be able to say: Forward! Let’s keep moving forward.”

Francis is the third pope to visit Catholic University. John Paul II visited in 1979, and Benedict XVI visited in 2008.

Before the Mass, people streamed from the nearby Metro station toward the basilica in the Brookland neighborhood, which is home to Catholic University. Clusters of Latinos stood together, chatting in Spanish while choral music echoed from the basilica. Many were excited to see the pope, but only a few said they were aware of Serra’s background or significance.

“The name is new to me, but it’s very interesting,” Alfredo Ortega, 49, said of Serra. More important to him was the fact that he was in line to see this pope with his mother, Maria Afay, 89. In the 1980s, his mother took him to their native Peru to see John Paul II when he visited there.

“She took me to see the pope then, and now it’s my turn to bring her,” Ortega said.

Lilia Chunves traveled from Woodbridge to see the canonization, though she too acknowledged never having heard of Serra. Yet, she also said that the pope’s canonization of Serra ensured that the monk “had to have been a good person.”

“This pope is all about goodness and family and making the world a better place,” she said. “He comes here with a noble spirit.”

Francisca Cruce, 55, described herself as an indigenous Andes Peruvian who grew up speaking Quechua and said she could not support Serra’s canonization.

“I know what he did to the Indians,” she said. But she added that she’s also Catholic, having converted after immigrating to the United States in 1980. Referring to the pope, she said, “I came because he is a person who brings a good message to the whole world, whoever wants to receive it. He’s open-minded.”

Yconne Segismundo, 25, a student at Gallaudet University, and Marga Marcial, 25, a front-desk officer at a hotel, came from nearby Mount Rainier, Md., to watch the pope on the big screen set up in a small, grassy area. Segismundo said she was moved by the pope’s homily, especially his plea to “stop the heart from going numb.”

“It was very inspirational,” Segis­mundo said. “He reminded everyone, like the canonized saint was saying, just to keep moving forward.”

After the Mass, Pope Francis greeted about 15 Native American men and women ranging in age from 25 to 70, said Andy Galvan, the museum curator for the Ohlone Tribe Mission in San Francisco.

Although Native Americans were treated poorly at the missions, he said, Serra himself did not mistreat them.

“He brought faith to my ancestors,” Galvan said, wearing a traditional feather cape and a necklace from his ancestors that he estimated was at least 300 years old. “I always knew he was a saint. I was just waiting for the church to declare him one.”

The pope gave rosaries to those gathered and then Galvan, who carried the relic of Serra during the Mass, said he kissed the papal ring.

“It was a magical moment,” said Galvan, 60. “It was like meeting my parish priest.”