The 25-year-old Suor Cristina is already a talent show sensation thanks to her habit-clad performances but also has on her side the critics, who say her popularity stems from novelty value.
"I have a gift and I am gifting it to you," the irrepressible Italian nun told a panel of shocked judges when she started out in March in the amateur contest.
Public enthusiasm has been high in this mainly Catholic country for her lustful cover versions including tunes from Flashdance and Dirty Dancing as well as Alicia Keys' "No One" and the 80s hit "Girls Just Want To Have Fun".
As the suspense mounted, the Italian sister said on Wednesday she was leaving her future "in the hands of providence" and would remain a "humble servant" if she wins.
She attributed her popularity to a "thirst for joy, for love, for a message that is beautiful and pure".
"Since Pope Francis talks of a bible of joy...I think I'm on the right track," said the small-town native from Sicily, who trained at a musical academy before becoming a nun.
Sister Cristina Scuccia, who is up against three other finalists, has also won celebrity endorsements including Whoopi Goldberg, the star of the comedy "Sister Act", who tweeted: "For when you want a taste of sister act".
http://t.co/UZHYvtr3tj For when you want a taste of sister act!— Whoopi Goldberg (@WhoopiGoldberg) March 21, 2014
Her performance of "No One" has received more than 50 million hits on YouTube and Keys said it was "pure energy".
The performances have also beaten viewing records at Rai Due public television with audience shares of up to 15 percent.
She has already sung alongside Kylie Minogue and Ricky Martin and a flirtatious panel judge, Italian rapper J-Ax said she could be the "holy water" to his "devil".
'Insult to showbusiness'
Fame has brought media attention to her past, including interviews with a former boyfriend and with Claudia Koll, the director of the musical academy where she trained - herself a former starlet who is now a lay sister.
"Cristina's personal journey has brought her to maturity and artistic fullness thanks to a mysterious and special force. By giving herself to the Lord, she has enriched her art," Koll from the Star Rose Academy said in a recent interview.
Suor Cristina has described herself as a former rebel who distanced herself from religion but then received her vocation when she auditioned for a part in a musical about the founder of the Ursuline Order, Saint Angela Merici.
She became a novice in 2009 and worked with poor children in Brazil before formally entering the order and still has to take her final vows even as a musical career beckons.
But the nun's popularity is not universal, even in Italy.
Singer Emma Marrone, who represented Italy in this year's Eurovision song contest, said her success was "an insult to showbusiness" because the nun was not talented enough.
There have also been misgivings among the panel judges and she has been propelled mainly thanks to viewer votes.
Suor Cristina herself has hinted she might prefer a return to a "normal life" singing "with young people in church".
"I will continue to sing wherever the Lord wants," she said.