May I?
The quote comes from a book entitled "How the Pope of Peace Traded in Blood" by Joseph McCabe.
McCabe was an English writer who spent some time training for the Catholic priesthood with the Franciscans but left and took up the cause of militant atheism.
From the link:
"One of the giants of not only English atheism, but world atheism, Joseph McCabe left a legacy of aggressive atheist and antireligious literature that remains fresh and insightful today. His many works-- he wrote nearly 250 books--could constitute a library of atheism by themselves."
Other books by McCabe:
The Popes and Their Church
Rome's Syllabus Of Condemned Opinions; The Last Blast Of The Catholic Church's Medieval Trumpet
A thoroughly balanced and objective source of information, you can be sure.
Those who would base their opinions on such works stand condemned by their own words.