Sister Helen Prejean has some advice for Pope Francis, who, six years into his papacy, still encounters resistance to his efforts to shake up the Catholic Church: “Be patient - it takes time!”

Just over one year ago, the pope officially declared the death penalty to be “inadmissible” and updated the catechism, the official compendium of Church teaching, to reflect the development. It’s something Prejean has been pushing for since she first began getting to know death row inmates in the 1980s.

Along the way, she’s learned a few lessons in patience, but also in persistence.

Prejean’s remarks came in an interview with Crux upon the release of her new memoir, River of Fire: My Spiritual Journey, published last month by Random House.

While she first found herself in the national spotlight for her memoir-turned-film, Dead Man Walking - in which she was famously played by Susan Sarandon - the Congregation of St. Joseph nun’s latest book is, in some respects, an effort to account for how she transformed from an introspective religious sister to a social justice warrior, and what’s sustained her along the way.

At age 80, Prejean isn’t slowing down. She’s still crisscrossing the country, she’s actively texting, using her iPad, Tweeting, and, perhaps most importantly, she’s still preaching - just not from a Catholic pulpit (more on that later).

Speaking to Crux, she says that in many ways, River of Fire is her effort to make sense of her own “slow awakening” to the needs around her in the world and the Second Vatican Council’s calling for engagement with them.

Until her forties, she recalls living a quiet life focused on prayer, leading and organizing retreats, limited to her “cocoon.”

Meanwhile, she began to see the work of religious sisters among the poor and marginalized in Latin America, risking their lives to work against dictators, and providing a Catholic witness in places where others were withdrawing.

Back in New Orleans, she began slowly to confront the fact that the poor were around her at home. Perhaps in addition to praying for God to help them, she began to think, she could actually do so herself.

Prejean began working in the housing projects, and eventually was asked if she’d be willing to correspond with an inmate on death row. She would go on to visit him and serve as his spiritual advisor, eventually accompanying him to his execution - an experience that would catapult her into becoming one of the world’s most vocal opponents of the death penalty.

Looking back, she credits the “unleashing” of the spirit of the Second Vatican Council with spurring her to action. Her memoir, she says, “shows how Vatican II pointed us back to social justice and to the gospel.”

“It also brought us back to the scriptures - it took us to the original source,” she continued. “And it reminded us that human experience shapes perspectives. When you move to the margins, or to the field hospital as Pope Francis says, you encounter people where they are.”

Drawing on her own experience of working with death row inmates and families who have experienced violence, Prejean has been no stranger to resistance, including those within the Church skeptical of her call for a total abolition of the death penalty.

But her involvement both with inmates in their final moments of life, as well as with family members who have been victims of heinous crimes yet see the death penalty as a state-sanctioned way of perpetuating violence and injustice, have led her to push ahead.

“That experience bubbles up and then finally you reach a point where you change it on paper,” she says, describing how, over time, the Church has reached a position of full and total opposition to the death penalty.

“Here’s what I discovered,” she recalls. “Even pro-life Catholics would draw a line between the innocent and the guilty,” saying this distinction was the “crux” of her conversation on the subject with Pope John Paul II in the nineties.

“Where is the dignity in that?” she asks of the idea that there are some crimes so terrible that the individuals who commit them must be killed.

“It’s a very arrogant assumption that the only option we have is to kill them,” says Prejean. “Who are we to make that assumption?” she asks.

Pope John Paul II would go on to agree with Prejean, saying that it was “both cruel and unnecessary.” Just over twenty years later, Francis would take it one step further, deeming it “inadmissible.”

For Prejean, this is proof that people - even popes - can eventually change their minds, and it’s worth trying to persuade them.

“People are not wedded to the state killing people,” she insists. “But people have been made to be afraid,” adding that the physical distance between prisoners and the general public often leads to a dehumanization.

“We need to see them face to face,” she says.

While she’s still keeping her eye on the fight against the death penalty, as a woman in the male-dominated Catholic Church, she’s also using her platform to advance the cause of women’s leadership, including writing a letter to Francis on the matter.

For Prejean, the fact that she’s traveled the globe preaching in pulpits of every Christian tradition but her own is “so blatantly, inherently sexist.”

“It’s also not healthy for the Church’s decision-making,” she said, noting the absence of women in senior positions of leadership in dioceses in the U.S. and in Rome.

Yet if her four decades long battle tangling with Church officials over the death penalty has taught her anything, it’s that “when you love a community, you stay at the table and dialogue and that’s how in time things can change.”

“Just think - it took 1,600 years for the Church to change on that front,” she says.

And looking ahead, she has no intentions of slowing down or staying silent, paraphrasing the Holocaust survivor and writer Elie Wiesel: “When we’re a witness to what others have not seen, we have a moral imperative to tell others.”

“That’s still my job,” says Prejean.