There is an essay attributed to Pope Francis circulating recently. He didn't write it. I have linked it via the Snopes discussion just to make sure you don't lose your head and think it's real.
There is a whole subscene over at the Official C S Lewis FB page dealing with quotes falsely attributed to Lewis. Quotes about peace and war get attributed to Einstein frequently. Lincoln, Churchill, and Gandhi often get their names slapped onto ideas that people want to puff up a bit and push into wider acceptance.
I find the ones attributed to Christians curious. The first sentence of "A Gentle Reminder" is "This life will go by fast." It just doesn't have the right ring to come from any pope, even this one who does sometimes utter thoughtless banalities when speaking off the cuff. (The writers over at "First Things" assure me he is better on his more careful, thought-through statements.) One of the false Lewis quote begins "You are never too old to dream a new dream..." I knew instantly that Lewis never said anything like that. Some of the fake quotes are not too far off, as CSL did write something like them. Yet some are just immediately impossible. When the quote-police (I am among them) come out, others get irritated, sometimes claiming that he might have said it somewhere that we just don't know about. Technically, yes, but really, no. There are any number of us at the site who have everything or nearly everything of Lewis's, and taken together, we would know. Also, the quote being shoved forward often has words or phrases that are clearly modern, that could not have been written before 1990.
But more than that, one can tell by some quality of the depth and the tone. There might be serious comments that would set us back for a time, because the phrasing and sentiment were possible. Yet these are seldom the issue. The superficialities, the poorly-understood theology, the cliches are far more frequent. When people protest that this sense that frequent readers of Lewis have is not something real, it is something we are making up, I have to conclude that they don't see the difference themselves because their own understanding of Lewis, and likely of theology or even of God is superficial. Or they want following Christ to not be much of a hardship, to be a matter of cheerfulness and no sacrifice.
They really think that a Pope would write a letter to his flock telling them to "allow dogs to get closer," and to "give yourselves the pleasures you deserve."