After taking the Internet by storm last fall with their hit "Confia en Dios," this group of singing sisters was invited to perform at Pope Francis' U.S.-Mexico border Mass in Juarez earlier this week.

"We are very happy…we never imagined that we would receive an invitation," Sister Mónica Nobl told CNA Feb. 17.

One of the leaders of the musical group "The Siervas," meaning "Servants," Nobl said that the invite to sing at the papal Mass was something none of them expected, but came through Facebook.

After checking out their Facebook page and seeing the viral video for their song "Confia en Dios," a priest from Mexico wrote them asking if they wanted to sing at the Pope's final Mass in Juarez.

The immediate reaction was "Of course! How can we not participate in this great event?" Sr. Monica said, adding that they were "very, very happy and very excited to participate."

The 12 sisters in the group are all part of the community of the Servants of the Plan of God. Founded Aug. 15, 1998, in Peru, the community lives a life of full apostolic availability, evangelizing in the areas of youth, the family and culture, with a special emphasis on the fragile, ill, poor and suffering.

Some of the more musical members of the community banded together, literally, last fall in order to put their musical talents to use in spreading the message of the Gospel.

In September 2015 "The Siervas" released their first CD in Spanish, "Ansias que queman," which a month later was presented with a tour in Ecuador, Colombia, Chile and Peru.

The biggest hit on the album is a song called "Confia en Dios," or "Trust in God." Since it was posted to YouTube in October, the music video for the song has been viewed over 365,000 times.

It shows the sisters playing both classical instruments as well as the drums and the electric and bass guitars while singing the catchy tune in their religious habits from a rooftop helipad.

Nobl explained that "The Siervas" composed the music and lyrics for the songs themselves, and that they chose a selection of different types of songs to perform for the Pope's Mass.

"We prepared a variety of songs to encourage people," she said, adding that "our rhythms are well motivated," since they are a mix of pop, rock and Latin pop genres.

The blend of rock with religious hymns has gained popularity among Catholics and non-Catholics alike.

Out of the many non-Catholic and non-religious people who have commented on the "Confia en Dios" music video, the majority say that despite not sharing the sisters' faith, they are big fans of the song and think it touches people on a human level.

What the group hopes to demonstrate is that even Catholic music "can be composed with the highest musical standards," Nobl said.

Because of this, the group is already recording their second album, which they chose to do in collaboration with renowned musical producers in both Peru and the United States.

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Although their community was founded in Peru, members of "The Siervas" hail from countries all over the world, including Argentina, China, the Philippines, Chile, Venezuela, Ecuador and Japan.

In addition to their gig in Juarez, the sisters will also play in several other Mexican cities as part of a mini tour that includes stops in Chihuahua, San Juan del Rio and Mexico City.

As part of their Mexican tour, "The Siervas" will also be performing charity work throughout the trip in soup kitchens and schools in the cities they visit.

Out of all the stops they will make, Nobl said that their performance in Juarez was especially significant not just because they played for the Pope, but also because of the suffering those who live in the city face on a daily basis.

To perform in a place like the violent and conflicted border between Mexico and the United States "excites us a lot because this is why we do music, so that the message of the faith arrives to and crosses borders, and arrives above all to those who suffer most," she said.

"Our mission is to help those in need. We assist poor people, those who suffer. So it is very meaningful and very symbolic for us to be in Ciudad Juarez, which suffers a lot."

With communities throughout the Americas, Europe, Asia and Africa, the sisters run numerous projects assisting marginalized groups, such as the homeless and those who live in extreme poverty, and have a school for disabled children.