US President Joe Biden, left, shakes hands with Pope Francis as they meet at the Vatican, Friday. Associated Press photo

The gesture between two of the world’s most powerful men was notable more for what it did not include than for what it did.

At the Vatican in July 1963, President John F. Kennedy and Pope Paul VI rose from their chairs and shook hands as cameras flashed and a videographer filmed.

Traditionally, Catholics like Kennedy were expected to greet the pope by kneeling, taking his right hand and kissing the papal ring, a symbol of the office. Decades later, questions remain about whether the president’s decision to shake the pontiff’s hand was meant as a statement that his faith and his service to the United States could coexist without, as critics ominously predicted, undue subservience to the Vatican.

The meeting Friday between President Joe Biden, the second Catholic to hold the nation’s highest office, and Pope Francis comes at a similarly contentious time — but in a nearly opposite way. While non-Catholics in the 20th century questioned whether Kennedy could avoid Vatican influence, the contemporary controversy centers on whether Biden’s break with his church on abortion rights undermines what he characterizes as his deep faith.

Following the lead of his two predecessors, Pope Francis typically discourages those greeting him from kissing the papal ring. But before the Second Vatican Council concluded in 1965, the gesture was considered a sign of respect and obedience.

It’s unclear how much Kennedy considered the symbolism of declining to greet Pope Paul VI that way, said Alan Price, director of the John F. Kennedy Presidential Library. Welcoming those he met for state meetings with a handshake was the president’s typical behavior.

There’s evidence that Kennedy was at least aware that his disposition toward the pope would draw scrutiny. He remarked sardonically to an aide before the visit that kneeling to kiss the papal ring “would get me a lot of votes in South Carolina,” a nod to the religion-based opposition to him in the South during his campaign.

Barbara Perry, director of presidential studies at the University of Virginia’s Miller Center, said it’s logical that Kennedy would have been wary of appearing too deferential to the pope. The president expected to run for reelection in 1964 and would need the votes of non-Catholics who were suspicious of his faith.

“He would know that that would be a bridge too far for him in the public eye and the eye of, particularly, Protestants in that day,” Perry, who is a scholar of the Kennedy family, said of the ring-kissing ritual.

At the time, anti-Catholic sentiment was widespread. New York Gov. Alfred Smith, a Democrat, was the only Catholic to have been the presidential nominee of a major party. Political cartoons in the 1960 election portrayed Kennedy doing Pope John XXIII’s bidding. After Kennedy won the West Virginia primary, during which he defended his faith, he declared that he had “buried the religion issue once and for all.”

But when he met Pope Paul VI more than two years into his presidency, Kennedy’s behavior was still closely watched. The editors of America magazine, run by the Jesuit order of Catholic priests, declared it disgraceful that the president would fail to greet the pope with traditional decorum.

“Little did the editors — or anyone else know or realize — that perhaps the pragmatist president and the diplomatic pope might have wanted it that way,” Joseph McAuley, an assistant editor for the magazine, wrote in 2015.

It hadn’t been a given that Kennedy would visit the Vatican during his presidency. He was only the third U.S. president to do so, and Perry said he would have been painfully aware that the meeting could be used against him in his reelection campaign. Kennedy may have figured that he had put that issue behind him after he won office the first time, she said.

“My sense is that he felt comfortable enough knowing that he had won and broken down the barrier on Roman Catholics becoming president, that he could meet with the pope and be photographed with him,” Perry said.

Kennedy was assassinated four months after the trip to the Vatican. Pope Paul VI later recounted his visit.

“We remember this young Head of State, modest and courteous, before us during our meeting; and still we see his serene and virile face immersed in deep thought,” the pontiff said in an interview with the Kennedy library. “He hesitated a long time, he spoke frankly and softly, like one who wishes to find the right words and to speak good words.”