Saioa Hernández has thought a lot about vocation. She has also tried a lot of different vocations on for size: a pilot in the Spanish Air Force, a music teacher and for a year and half, a nun.

This was all before her soaring career as an opera singer, which takes her critically acclaimed soprano voice around the world in roles from Gioconda to Lady Macbeth, from the Sydney Opera House in Australia to Teatro alla Scala in Italy. 

On Nov. 1, she made her debut at New York City’s Metropolitan Opera in the titular role of Giacomo Puccini’s “Tosca.”

Ms. Hernández grew up in Madrid, Spain, the middle child between two brothers.

“When you are the only woman in the middle of two brothers, you have to be very strong,” she said with a laugh, sitting on the red velvet steps of the Met Opera’s lobby for an interview with America.

Ms. Hernández was raised Catholic—mostly. Her parents were married in the church, had her and her siblings baptized and took them to Mass, but Ms. Hernández’s connection to the faith was tenuous at best. When a close friend decided to leave the church as a teenager, she left too. 

But she found her way back to the faith after falling in with a group of Catholic scouts while attending university. Under their guidance and through the community she formed with them, something sparked.

“I began to feel my faith, and I began to have a conversion,” she said. 

Ms. Hernández received her first Communion at 19 on the Camino de Santiago with the scouts. She would join the novitiate just two years later, though the track from communion to convent is not an easy one to trace.

“It’s difficult to explain this because everything was in the middle of other things,” she said. 

On one hand, she was considering joining the Spanish Air Force, and, in fact, took several exams to join before ultimately deciding it wasn’t for her. During this time, she was also regularly singing in the chorus at her university—“the reason I decided to enter in that university was because they have a wonderful chorus”—though that was still just a hobby for her at the time. 

And during all of that, she was navigating her religious conversion. 

“It was a very complicated [path]—even for my parents and my family, because it was not easy to tell your parents, ‘Okay, now I want to try this, then I want to be this,’” Ms. Hernández said. “And it was difficult for me too, of course”

Finding her vocation was the defining struggle of Ms. Hernández’s youth. She remembers clearly someone asking her as a teenager what she wanted to do with her future and being frightened by her own inability to answer.

“I thought, ‘Okay, [I need to] find my vocation, my real vocation, so the thing that comes naturally,’” Ms. Hernández said. “Vocation is what you have on you, the thing that God calls you to do in the world, to give to the world. I wanted to find my vocation to make my job be not only a job but something that occupies all my life.”

So after taking two years to further discern her faith and find out what kind of religious order she might want to enter, cloistered or active apostolic—“I was attracted to every one of them,” she recalled with a laugh—Ms. Hernández joined a convent with the Missionaries of Christ the Priest in Las Rozas, Spain, to become a woman religious.

She remembers the year and a half that she spent there very fondly. 

“I was very happy being there, and I think it was one of the best year and a halfs that happened in my life, because I learned a lot about me, about patience—because I was not very patient in my life, even—about my relationship with others, and of course with God,” Ms. Hernández said. “I think it was a very beautiful period to learn many, many, many things about life, about why we are here in this world.”

Saioa Hernández in the title role of Puccini’s “Tosca.” Credit: (Marty Sohl / Met Opera)

The fact that her time in the convent was an exceptionally positive experience made her decision to leave an exceptionally difficult one.

“I was living very happily there, but I discovered that maybe I was too comfortable, and maybe I needed to do something different,” Ms. Hernández said. 

In other words, she still had not found her vocation.

As she began contemplating her next steps, she noticed a through-line in the different vocations she had pursued thus far. 

“I was trying to enter the Air Force, and when I decided to leave, I returned to the chorus. When I entered the convent, I left the chorus, but when I returned to my life in my parents’ house, I returned to the chorus. So I was always returning to the chorus,” Ms. Hernández recounted.

The path to opera wasn’t immediately apparent, though. Ms. Hernández enjoyed singing as a hobby, but she was content to stick to where she could hide within a group of others and behind her libretto. So she began studying to become a music teacher. 

But it was while she was teaching that someone approached her to join a monthlong tour of the opera “La Traviata” as a member of the chorus. It was a beguiling offer—a summer traveling through France with a company of singers.

“I never did opera before, so it will be fun,” she recalls thinking.

“And from the first time I put my feet on the stage with the dress of the chorus, I said, ‘Oh my God, this is what I was looking for. This is the thing that I want to do all my life,’” Ms. Hernández said. “I remember perfectly how I felt in that moment because I felt complete. So it was like, ‘Yes, I want to do it all my life. I’m done.’”

She had found her vocation. 

Returning home after the tour, Ms. Hernández had no doubt—she would train to become an opera soloist. Needless to say, the choice has paid off. 

Ms. Hernández is a dramatic force as Floria Tosca, with an impressive knack for plucking the funny bits from an otherwise macabre three acts.

Vocally, she leaves nothing behind, at times filling the whole of the Met with her stadium-soprano, otherwise teasing a falsetto so startlingly fragile, and in wisps so delicately clipped, as to capture the drama of “Tosca” in her sound alone. 

There are some clear parallels between Saioa Hernández and Floria Tosca. Placing the most immediate of these parallels aside—in the 1887 play on which the 1900 opera is based, Tosca spends her youth with Benedictine nuns before becoming an acclaimed talent in the opera—Ms. Hernández locates a familiar sensitivity and honesty in the role.

“I think she is very natural, and she lives her faith in a very natural way,” Ms. Hernández said. “Not only her faith, but her feelings. She’s very spontaneous. She passes from feeling love [to] jealousy [to] fear, and then she’s very courageous. She passes from one thing to the other in a very easy way, and I think I’m a bit like this too.”

Ms. Hernández said talking about her faith is not always easy.

“Especially in Spain, I think to be Catholic is not easy to tell to others because it seems that you are from another world,” Ms. Hernández said. “That you are not thinking clearly or something like that. And people think that maybe you are a bit naive.”

But increasingly, she chooses to discuss her Catholic faith more openly, especially the parts of it that guided her journey, because she believes everyone could benefit from more vocational discernment in the world today.

“I think vocation is the center of everything, because if everybody finds his vocation, her vocation, you will be happier,” Ms. Hernández said. “There’s nothing more special than to find your special light and give it to the others. It connects you with God, with yourself, and with others.”

Will Martino is a Joseph A. O’Hare, S.J., fellow at America Media.