Pope Francis waves as he arrives to lead his Wednesday general audience in Saint Peter's Square at the Vatican, June 17, 2015.

This sermon doesn't amount to much, apparently.

As little as 10% of donations by Roman Catholics that are specifically advertised as helping the poor and suffering actually go toward charitable work, a new report says.

About two-thirds of the rest of the $55 million in donations for Pope Francis' annual charitable appeal, known as Peter's Pence, is used to fill the Vatican's administrative budget deficit, The Wall Street Journal reported in an article Wednesday, citing sources familiar with the spending.

The newspaper said that the use of Peter's Pence for the budget "is raising concern among some Catholic Church leaders that the faithful are being misled about the use of their donations, which could further hurt the credibility of the Vatican's financial management under Pope Francis."

A spokesman for the Vatican's mission to the United Nations did not immediately respond to a request for comment from CNBC about the Journal's report. The article noted that under church law, a pope can use Peter's Pence in any manner that serves his ministry.

The Journal, citing people familiar with the funds' use, said that the assets of Peter's Pence have dwindled since Francis became pope in 2013 from more than $775 million to $665 million.

Meanwhile, the Holy See's deficit in 2018 doubled to more than $76 million on a budget of around $333 million.

Last month, Francis replaced the Vatican's top financial regulator on the heels of a financial scandal involving the church's London real estate investments.

Peter's Pence is a special collection from Roman Catholics every June.

According to the collection's website, it is "A Day for the Works of Charity."

"These collections and donations by the individual faithful or entire local churches raise the awareness that all the baptized are called to materially sustain the work of evangelization and at the same time to help the poor in whatever way is possible," the site says.

"It is an ancient practice which began with the first community of the apostles. It continues to be repeated because charity distinguishes the disciples of Jesus," the site says.

The site then quotes Jesus' words in the Gospel of John, "From this, they will all know that you are my disciples, if you have love for one another."