He carries a rosary in his pocket, one that belonged to his dead son, Beau. On election day last Tuesday, he went to mass, as he does every Sunday.
In his victory speech on Saturday night, he quoted from Ecclesiastes: “The Bible tells us that to everything there is a season – a time to build, a time to reap, a time to sow. And a time to heal. This is the time to heal in America.”
For only the second time in US history, a Catholic will occupy the White House when Joe Biden is sworn in as the country’s 46th president. A man of profound faith, he has pledged to restore the “soul of the nation” after four years of rancour.
At his side will be a vice-president who, as well as being the first woman of colour to hold the position, comes from a family that has embraced the Baptist church, Hinduism and Judaism.
Catholic bishops in the US were quick to congratulate the president-elect, acknowledging that he will be only the second president to be a Catholic, John F Kennedy being the first.
“At this moment in American history, Catholics have a special duty to be peacemakers, to promote fraternity and mutual trust, and to pray for a renewed spirit of true patriotism in our country,” said José Gomez, archbishop of Los Angeles and president of the US Conference of Catholic Bishops.
Biden’s Catholicism is at the core of his life and is likely to shape the way he governs as president.
“I’m as much a cultural Catholic as I am a theological Catholic,” he wrote in his book, Promises to Keep: On Life and Politics. “My idea of self, of family, of community, of the wider world comes straight from my religion. It’s not so much the Bible, the beatitudes, the Ten Commandments, the sacraments, or the prayers I learned. It’s the culture.”
Less than two weeks ago, in an article for the Christian Post, Biden wrote: “My Catholic faith drilled into me a core truth – that every person on earth is equal in rights and dignity, because we are all beloved children of God.”
As president, he added: “These are the principles that will shape all that I do, and my faith will continue to serve as my anchor, as it has my entire life.”
Several of Biden’s campaign ads featured footage of his meetings with Pope Francis. In a 2015 interview, Biden said Francis was “the embodiment of Catholic social doctrine that I was raised with. The idea that everyone’s entitled to dignity, that the poor should be given special preference, that you have an obligation to reach out and be inclusive.”
At the Democratic convention in August, when Biden was formally adopted as the party’s candidate in the presidential race, his friend and successor as a Delaware senator, Chris Coons, said Biden’s faith was not “a prop or political tool”.
“Joe’s faith is really about our future, about a world with less suffering and more justice, where we’re better stewards of creation, where we have a more just immigration policy and where we call out and confront the original sins of this nation, the sins of slavery and racism. Joe knows these are central issues in this election. And for him, they’re rooted in faith,” Coons said.
Some conservative Catholic organisations urged followers not to cast their votes for Biden because of his pro-choice stance on abortion – although a majority of US Catholics say abortion should be legal in all or most cases, according to the Pew Research Center.
Biden has said he personally believes life begins at conception but recognises others do not share his view. “What I’m not prepared to do is impose a precise view that is borne out of my faith on other people,” he said in a 2015 interview with America magazine.
Biden has not always been a champion of LGBT+ rights, but he now supports same sex marriage and has pledged to enact the Equality Act within 100 days of becoming president. He will be the “most pro-equality president we have ever had”, according to LGBT rights campaigner Chad Griffin.
His Catholicism and Irish roots appear to have appealed to voters in strongly culturally Catholic rust belt states such as Pennsylvania. Just over half of US Catholics (51%) voted for Biden last week, compared with 45% who voted Democrat in 2016; and 47% voted for Trump this time, compared with 52% in the previous election, according to exit polls.
Biden has frequently said his faith had helped him cope with personal tragedies, including the death of his first wife and daughter in a 1972 car crash and again in 2015 when his son, Beau, died from cancer.
Anthea Butler, professor of religious studies at the University of Pennsylvania, said Biden’s language of hope and healing “speaks a lot to his Catholic faith”. She told BBC Radio 4’s Sunday programme: “I think he wants to set a tone that is not simply conciliatory but that is faith-based.”
Kamala Harris, who will be Biden’s vice-president from January, identifies as a black Baptist, with a family background of Hinduism and Christianity. She is married to a Jewish man.
“This speaks to the ways in which religion is fluid in America, and the ways in which people are holding things together in interfaith marriages and interfaith families,” said Butler.