Not since Jimmy Carter, a Baptist who has taught Bible classes well into his 90s, has the United States had a president whose life is so entwined with his faith as Joe Biden.
A devout Catholic, the 78-year-old Biden is as apt to quote Scripture as he is his beloved Irish poets.
Just the second Catholic president in US history -- John F. Kennedy was the first -- Biden wears his faith on his sleeve.
Literally.
Around his left wrist he often sports a rosary from the Basilica of Our Lady of Guadalupe in Mexico that his son Beau was wearing the day he died of brain cancer in 2015.
He frequently credits his working-class Irish Catholic roots with shaping his values on social and economic issues.
Biden rarely misses a Sunday mass when at home in Delaware, attending services at St. Joseph on the Brandywine, a small, quaint church in an affluent suburb.
It is there that Biden's parents are buried along with Beau. Also there are the graves of Biden's first wife, Neilia, and their daughter Naomi, who were killed in a 1972 traffic accident.
Beau and his brother Hunter survived the crash.
Biden took the oath of office on Wednesday as the 46th president of the United States with his left hand on a colossal 19th-century family Bible held by his wife, Jill.
His inauguration address included several biblical references and he paused his speech for a moment of silent prayer for the 400,000 people in the United States who have died of coronavirus.
Biden started his first full day at work in the White House on Thursday by watching a virtual prayer service at the National Cathedral with Vice President Kamala Harris.
'Understanding, reconciliation, peace'
Biden made it clear from the outset that as president he will not hesitate to use the power of religion to help bridge the gaping chasm between Republicans and Democrats left by Donald Trump's attempts to subvert the presidential election.
He invited congressional leaders -- including top Republicans -- to attend services at St. Matthew's Cathedral, a Catholic Church in Washington, on the morning of his inauguration.
Mitch McConnell and Kevin McCarthy, respective Republican leaders in the Senate and House, both accepted the invitation instead of attending departure ceremonies for Trump.
The political divide is not the only one Biden faces as he takes office.
His inauguration was met with mixed messages from Pope Francis and the president of the US Conference of Catholic Bishops (USCCB).
Francis, in a message warmly congratulating Biden, expressed hope that his decisions "will be guided by a concern for building a society marked by authentic justice and freedom."
Recognizing that Biden has his work cut out for him, the pontiff wished him success in fostering "understanding, reconciliation and peace within the United States."
Jose Gomez, Archbishop of Los Angeles and president of the USCCB, said he was inspired by how Biden's faith has "brought him solace in times of darkness and tragedy."
"He is our first president in 60 years to profess the Catholic faith," Gomez said in a statement.
"In a time of growing and aggressive secularism in American culture, when religious believers face many challenges, it will be refreshing to engage with a president who clearly understands, in a deep and personal way, the importance of religious faith and institutions," he said.
Gomez stressed, however, that the USCCB has differences of opinion with Biden on several issues important to the Church, particularly abortion.
Biden supports the landmark 1973 US Supreme Court decision which affirmed a woman's right to an abortion -- a position that led most evangelical Christians to support the anti-abortion Trump in the November election along with nearly 50 percent of Catholics.
"Our new president has pledged to pursue certain policies that would advance moral evils and threaten human life and dignity, most seriously in the areas of abortion, contraception, marriage and gender," Gomez said.
The USCCB president's statement was in sharp contrast to that of the Pope and came under fire from some other prominent figures in the US Catholic Church.
The archbishop of Chicago, Cardinal Blase Cupich, called it "ill-considered" and a "surprise to many bishops."