For decades, two men were charismatic figures on the world stage, full of vitality and admired by millions, if not billions, of people: One was a boxer, the other a pope.

In their twilight years, both had the same debilitating illness that left them visibly weak, but they remained public figures, offering witness to a different kind of strength, and a different kind of victory.

Muhammad Ali, the graceful former world heavyweight boxing champion, died June 3 in Scottsdale, Arizona at the age of 74 after suffering for more than three decades from Parkinson’s disease. Saint John Paul II died in Rome 11 years earlier in 2005 at the age of 84 after a similar public battle with that illness.

The two men met and exchanged autographs with each other in 1982, but ultimately they shared something much deeper, in the way they endured suffering.

One of Ali’s last appearances before a mass TV audience came at the 1996 Summer Olympics in Atlanta, when the crowd gathered at the opening ceremony offered a thunderous ovation as the retired boxer appeared and held the Olympic torch aloft with his right hand to light the cauldron, while his left hand and arm shook uncontrollably.

NBC sports anchor Bob Costas, noting the boxing champion’s Parkinson symptoms, said Ali still exuded nobility, and the crowd responded with affection and respect at that exciting moment that signaled the beginning of those Olympic games.

Pope John Paul II’s last public appearance was no less poignant. The Saint John Paul II National Shrine in Washington has a special exhibit tracing that pontiff’s life and legacy, including a film clip of him appearing in his window at Easter in 2005, with the once vigorous pope trembling and too weak to recite one last blessing to the crowd gathered in St. Peter’s Square.

He died six days later, on the vigil of Divine Mercy Sunday.

George Weigel – the author of Witness to Hope: The Biography of Pope John Paul II and its sequel, The End and the Beginning: Pope John Paul II – The Victory of Freedom, the Last Years, the Legacy – told Crux, “The pope’s refusal to hide his disease and what it was doing to him – in fact, the way he turned his infirmity into an act of witness to the human dignity he had long proclaimed – was his last ‘living’ encyclical.”

Two pro-life leaders interviewed by Crux said the public witness of courage in the face of suffering by the former pope and boxing champion offer an enduring lesson to the dignity of human life in all its stages and conditions. They said that message is all the more vital today, as groups like Compassion & Choices are lobbying state legislatures across the country to legalize physician-assisted suicide.

“Muhammad Ali and Pope John Paul II showed even if you have difficult times, life is precious, and life is worth living,” Carol Tobias, the president of the National Right to Life Committee, said in an interview with Crux.

“They weren’t ashamed of what this disease was doing to their bodies,” she said, adding that their example demonstrated that having a serious illness or disability “doesn’t make you less of a human being or (mean) that your life has less value.”

Their public witness offered hope and encouragement to people facing illnesses and disabilities, Tobias said. “They cared about people and wanted to use this illness to help others,” she said.

A pope who had inspired the world as a spiritual leader and a boxer admired for his exploits in the ring and his humanitarian efforts outside it, achieved a different kind of triumph in their weakness, she said.

“The victory came in the way these two men lived their lives and showed others even if you have challenges, you don’t have to give up.”

Tobias said the pope and boxer also showed people that the way to respond to people who are suffering is “with love and care and help.”

In his 1995 encyclical Evangelium Vitae – Latin for “The Gospel of Life” – St. John Paul II warned of a growing culture of death in the world, and he encouraged Christians and other people of goodwill to counter that trend by helping to build a civilization of life and love.

The pontiff spoke out forcefully against assisted suicide, saying, “True ‘compassion’ leads to sharing another’s pain; it does not kill the person whose suffering we cannot bear.”

In that encyclical, the pope also wrote, “We are asked to love and honor the life of every man and woman and to work with perseverance and courage so that our time, marked by all too many signs of death, may at last witness the establishment of a new culture of life, the fruit of the culture of truth and of love.”

The Polish-born pope, whose moral strength and leadership helped topple Communism in Eastern Europe, and whose vitality captivated millions at World Youth Day gatherings, in his last years through his frailty demonstrated the Gospel of Life that he had championed.

Ali, a devout Muslim whose opposition to war and racism inspired people of all backgrounds, ensured his boxing immortality with three epic slugfests against Joe Frazier, with his upset defeat of George Foreman, and with his clever wordplay, such as his famous “float like a butterfly, sting like a bee” taunt.

As his Parkinson’s progressed, Ali continued to make public appearances, such as appearing before a Senate committee in 2002 to encourage more funding of research to find a cure for the disease, and receiving the Presidential Medal of Freedom in 2005.

After the boxer’s death, a Muslim religious leader told the Catholic News Agency that Ali acknowledged that his illness was a blessing that showed him that God was really “The Greatest,” and the boxing champion relied on his faith to face what some commentators called the greatest fight of his life – his battle with Parkinson’s disease.

The boxer and his wife supported the establishment of the Lonnie and Muhammad Ali Parkinson Center at the Barrow Neurological Institute in Phoenix, to support research on the disease and to help fellow patients and caregivers.

Both world figures known for their eloquence had difficulty speaking in their last years, and the men once known for their vigor – St. John Paul liked to go skiing and hiking as pope – had difficulty walking as their disease progressed. But even as their movements became more and more unsteady and their voices weakened, their presence continued to inspire people.

Greg Schleppenbach, the associate director of the Secretariat of Pro-Life Activities at the U.S. Conference of Catholic Bishops, said the pope and boxer by their public witness demonstrated their belief in “God as the master of their life and death.”

With that faith, they embraced their suffering and used it to try to inspire others, the pro-life leader said, adding, “We live in a time when we so desperately need witnesses of heroic virtue.”

St. John Paul II’s example, he said, underscored the Christian belief in how Jesus, who healed the sick, also redeemed the world through his own suffering and death. Schleppenbach said the pope, by openly showing his illness, “inspired millions of people with the hope of our faith and the hope of eternal life.”

The pope’s “Gospel of Life” described compassion as the ability to suffer and love with another, Schleppenbach said, noting that the Catholic faith calls on believers to reach out with love to the weak and vulnerable – like the terminally ill, people with disabilities, unborn children, and those living in poverty – and not regard them as burdens.

“We don’t derive our dignity as human beings by what we can do, but by who we are, and we are precious gifts from God, regardless of our level of development or abilities, or lack thereof,” he said.

The lives of Saint John Paul II and Muhammad Ali ended with demonstrations of love.

As the pope was dying, crowds of people gathered in St. Peter’s Square to pray for him. Ali’s family surrounded his deathbed as he died, with his daughter Hana later tweeting that they hugged and kissed him, held his hands, and chanted Islamic prayers.

She said they told him, “You can go back to God now.”

Hana Ali said that her father’s heart kept beating 30 minutes after all his other organs had failed, which she saw as “a true testament to the strength of his spirit and will.”