The Diocese of Scranton recently celebrated the feast of St. Peter Claver, who was known for his missionary work as a Jesuit priest in South America administering and preaching the Catholic faith to slaves.

“St. Peter Claver baptized and taught the faith to over 300,000 slaves over a period of 40 years,” the diocese tweeted.

St. Peter Claver was born in 1581 in Verdú, Spain. He became a Jesuit priest in 1616 and did missionary work in Cartagena, Colombia. There, Peter saw the horrors of the slave trade and dedicated himself to helping those enslaved, according to Britannica.

He spread the Catholic faith while taking care of the sick and keeping company with the slaves in Colombia. It is estimated that he converted and baptized over 300,000 slaves. St. Peter Claver was canonized by Pope Leo XIII and in 1896 declared him “patron of all Roman Catholic missions to African peoples” Britannica adds. He died in Cartagena in 1654.

Jesuits.org describes St. Peter Claver’s life as a missionary to slaves. In the 17th century many European colonists took part in the slave trade despite Pope Paul III’s condemnation of the practice. The Jesuits (Society of Jesus) admit that their order enslaved many in the 17th century. Today, they refer to that as a “deeply regretful chapter.”

St. Peter worked with enslaved people, saying “We must speak to them with our hands, before we try to speak to them with our lips,” the website says. He baptized many children on the slave ships that he lived on.

St. Peter’s humility and dedication to the less fortunate — especially slaves — led him to possess miraculous abilities, says Jesuits.org. They claim he would heal the sick just as Christ did.

John Grondelski, in an article for the National Catholic Register (NCR), cites St. Peter Claver’s life as an example of perseverance while the Church and the state battled over the issue of slavery.

“It would still take three centuries for much of the world to recognize the incongruity between human dignity and slavery, something Claver already knew,” Grondelski says. “And slavery continues, in various forms under different names, today. Our own society, too, can be blind to its moral failings: I am certain there will be a day when people look back on the 20th and 21st century to ask, ‘How could they believe killing their unborn babies was a ‘human right?’ Perhaps we still have something to learn from Peter Claver: about persistence in our time and patience in God’s.”