First, I would not mind if this were true.
The key to the truth of it is whether the statement is true or false is in these two sources:
Pietro Cardinal Bembo (Letters and Comments on Pope Leo X, 1842)
Paolo Cardinal Giovio (De Vita Leonis Decimi, Pontificus Maximus, Paolo Giovio, 1897 English ed., lib. iv, pp. 96-99).
Unfortunately neither appear to be online in the English (they may be online in the Latin).
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As for santitized Catholic histories, of Leo X, or anyone else, I care nothing. It is what I dislike about Catholicism the most: the incessant refusal to tell the facts straight, and the endless duplicity and concealment and propaganda
designed to elevate the Catholic Church and / or the Papacy and minimize its sins.
Yet, in the first Catholic Enclyopedia of 1907, Vol. 9, p.162ff, concerning Leo X,
here, the pagan traits of Leo X are
scarcely hidden, frankly hinted at, although not fully disclosed. (In addition to the below it is also recorded how Leo X drained the papal treasury, and more, by his profligate spending.)
"The unwieldy body is supported by thin legs. His movements were sluggish and during ecclesiastical functions his corpulence made him constantly wipe the perspiration from his face and hands, to the distress of the bystanders. But when he laughed or spoke the unpleasant impression vanished. He had an agreeable voice, knew how to express himself with elegance and vivacity, and his manner was easy and gracious. " Let us enjoy the papacy since God has given it to us", he is said to have remarked after his election. The Venetian ambassador who related this of him was not un biased, nor was he in Rome at the time, nevertheless the phrase illustrates fairly the pope's pleasure-loving nature and the lack of seriousness that characterized him. He paid no attention to the dangers threatening the papacy, and gave himself up unrestrainedly to amusements, that were provided in lavish abundance.
He was possessed by an insatiable love of pleasure, that distinctive trait of his family. Music, the theatre, art, and poetry appealed to him as to any pampered worldling. Though temperate himself, he loved to give banquets and expensive entertainments, accompanied by revelry and carousing; and notwithstanding his indolence he had a strong passion for the chase, which he conducted every year on the largest scale. From his youth he was an enthusiastic lover of music and attracted to his court the most distinguished musicians. At table he enjoyed hearing improvisations, and though it is hard to believe, in view of his dignity and his artistic tastes, the fact remains that he enjoyed also the flat and absurd jokes of buffoons. Their loose speech and incredible appetites delighted him. In ridicule and caricature he was him- self a master. Pageantry, dear to the pleasure-seeking Romans, bull-fights, and the like, were not neglected. Every year he amused himself during the carnival with masques, music, theatrical perform- ances, dances, and races. Even during the troubled years of 1520 and 1521 he kept up this frivolous life. In 1520 he took part in unusually brilliant festivities. Theatrical representations, with agreeable music and graceful dancing, were his favourite diversions. The papal palace became a theatre and the pope did not hesitate to attend such improper plays as the immoral ' ' Calendra " by Bibbiena and Ariosto's indecent " Suppositi."
However, historical accuracy is important.
Your Wikipedia source said this is:
Disputed.
https://en.wikiquote.org/wiki/Pope_Leo_X
And that is a bit of an understatement.
Yes, the references of these anti-Catholics are sometimes absurd. What on earth is this (assumed precursor to)" Catholic Encyclopedia, Pecci Ed."? No date, no real title, no publisher, no nothing. Perverse.
Assuming Pecci is Leo XIII(?) I have no idea what the actual title of this reference is.
(However carelessness is no reason to impute them with deliberate lying.)
Check out "Non caruit etiam infamia, quod parum honeste nonnullos e cubiculariis (erant enim e tota Italia nobilissimi) adamare, et cum his tenerius atque libere iocari videretur."
He was not without infamy, too, because he seemed to fall in love with some of his chamberlains (for they were the most noble of all Italy) and to joke more tenderly and freely with them.
from
Paulus Jovius Vita De Leonis X
Little of this really pans out.
We are looking at a paragraph on Wiki followed by:
The Criminal History of the Papacy - Part 3 of 3 (2007)
Tony Bushby
https://www.bibliotecapleyades.net/vatican/esp_vatican30c.htm
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You can work with:
John Bale
https://en.wikipedia.org/wiki/John_Bale
Acta romanorum Pontificum (1558)
By John Bale
https://books.google.com/books?id=OtE5AAAAcAAJ&pg=PA381
Leo Decimus
=======================
Nothing Tony Bushby writes can be taken at face. He picks up information from automatic writing and basically just makes things up. He put this “quote” on the cover of his Bible Fraud book. My letter on his nonsense about the Forged Origins of the New Testament was published in 2007.
This will help you understand his methodology.
BCHF
Fakes Source Citations
http://earlywritings.com/forum/viewtopic.php?f=3&t=422
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Did Pope Leo X say that Christianity is a fable?
Skeptics Stack Exchange
https://skeptics.stackexchange.com/questions/30416/did-pope-leo-x-say-that-christianity-is-a-fable
Note that the Baronius
Annales ecclesiastici
https://en.wikipedia.org/wiki/Annales_Ecclesiastici
was continued by Bzovius, a point missed when it is said Baronius only did 12 volumes through 1198.
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When you search, if you include "Roger Pearse" in the search, generally you will find quality info. He had very nicely debunked a similar quote used against Eusebius, so I figgered he was on this one.
Roger Pearse discussion on Google Groups
https://groups.google.com/g/soc.history.ancient/c/NiKwZ9dNcVE?hl=en#07f984fd0ecf6926
His post works with Johann Burchard and the idea that this goes to Alexander VI, not Leo X.
As to facts, Johann Burchard is to Alexander VI what Bembo is to Leo X. If the source is Bembo, it is Leo X. If Burchard, it is Alexander VI. I have read Burchard and cannot remember such a saying being attributed to Alex VI (but plenty of other incriminating stuff).
Tekton (James Patrick Holding)
https://www.tektonics.org/lp/popeleox.php
JPH works through many of the claimed sources.
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At last, a worthy source of info. Thanks for that link above.