Mythologies are full of events that could be interpreted, if they happened instead within the last six plus decades, as a UFO event. The 'Star of Bethlehem' and 'Wheel of Ezekiel' are both cases in point from Biblical mythology. Many of the mythological 'gods' or characters rode around in aerial or fiery chariots, perhaps akin to what was seen at Fatima in 1917. A UFO chariot by any other name is still a UFO chariot even if by 1917 no one interprets unknown flying (or dancing) lights in the sky as actual 'chariots'. On the other hand, the phrases 'unidentified flying objects' or 'flying saucers' weren't yet in vogue. So post 'chariot' mythology, yet pre our modern UFO era, we have neither 'chariots' nor 'flying saucers' but perhaps a dancing Sun.
Okay, so we have possible Biblical, therefore religious, UFOs associated with Ezekiel (that 'Wheel'), the Birth of Christ ('Star' of Bethlehem), Jonah (inside the belly of the UFO), and Joshua (who was provided some additional illumination by some UFOs). Another classic and more plausible UFO event in a religious context was the so-called 'miracle of the Sun' which occurred on 13 October 1917 near Fatima in Portugal.
As the story goes and unfolds, we have three children out mucking about in the fields doing your typical child thing (actually they were herding sheep) when behold they receive a vision of a lovely lady in May 1917 who is reputed to be the Virgin Mary. They receive all sorts of wondrous messages and prophecies from her as well as being required to do rituals of prayer and penance and all those other things required of the faithful. Of course who is going to take the word of three kids regarding their visions which kept repeating monthly like a stuck LP? It takes a little while, a while which also included some rather brutal treatment of the kids at the hands of officialdom, but the kids finally convince their elders and Doubting Thomas's that they aren't pulling pranks and are really telling the God's honest truth! But, to put the matter to rest, a miracle was promised by the Virgin Mary (otherwise called 'Our Lady of Fatima') as related by those three young children to occur on that date - the 13th of October noted above - at High Noon (if I recall correctly).
Of course a large and expectant crowd gathered on the commons to witness whatever miracle was about to unfold. Although the weather on the day was petty wet, just in time the Sun broke through the thinning overcast clouds and made an appearance. The gathered crowd, some 30,000 to 100,000 in number (the usual figure is given as roughly 70,000) saw some highly unusual luminous phenomena. Witnesses spoke of the Sun appearing to change colors, rotate like a wheel, and do zigzags and in general perform an aerial version of the tango. Now a key point being here those witnesses were able to actually look directly with no discomfort at the Sun - if Sun it was.
Now not everyone saw the same things, and witnesses gave widely varying descriptions of the 'Sun's dance'. Not all witnesses reported in fact seeing the Sun 'dance'. Some people only saw the radiant colors, and others, including some believers, saw nothing at all. The phenomenon (in various guises) however was claimed to have been witnessed by most people in the crowd as well as by people many miles away.
However, and why is this of little surprise, no movement or other phenomenon of the Sun was registered by scientists at the time. Since scientists observed no actual movement of the Sun; since it was a generally overcast day, it's probable the witnesses to the 'Sun dance' and the changing of the colors, wasn't the real Sun at all but was a bona-fide UFO, making an appearance on schedule to bring credibility to the prophecy, the kids and the apparently supernatural nature of the Virgin Mary apparition.
Since it's blatantly clear that a 'dancing Sun' is a violation of celestial physics some other explanation(s) have to be advanced to account for what happened. Could it have been a UFO?
Here are your options: 1) A Supernatural God, on behalf of His favourite girl, the Virgin Mary, works a miracle and allows a whole lot of people to watch the Sun do cartwheels in defiance of celestial physics; 2) There was no such event in reality and witnesses were smoking a bit too much of the good stuff - the option any sane betting person would take except it's hard to discount 70,000 eyewitnesses and the many statements attesting to the event which are on the public record; 3) the story has some sort of foundation, in which case the violation of basic celestial physics - the Sun doesn't and can't dance in the sky - was only apparent and had to have been something else. Sceptics suggest it was anything from mass hallucinations/wishful thinking, to false images caused by staring at the real Sun to an optical phenomenon called a mock sun or sundog (though that would be a hell of a coincidence). But, perhaps that something else, had it been post-June 1947, might have been termed a UFO.
One cautionary note which is probably not overly relevant but for what it's worth, I've been briefly fooled on two separate occasions by an optical illusion caused by a combination of a rapidly moving overcast or broken cloud cover and a stationary light source. In the first case, the disc of the Sun was just barely visible through the rapidly moving overcast. The second case involved stars seen through a rapidly moving broken cloud cover. The illusion is that you can fool yourself into thinking that it's the cloud cover that's stationary, and, in my two cases, the disc and the stars that were actually moving. The probable flaws here as Fatima explanations is that the illusion provides linear motion not erratic movements; you quickly realise your error when it's obvious you're watching what you think is a rapidly moving object yet the position/tilt of your head acim shift at all, even after several minutes, thereby confirming that the object wasn't moving at all.
But wait, there's more! In addition to the Sun doing a zigzag tango, apparently all the rather (just before the big event) wet to the core witnesses and the rather soggy and muddy ground near instantly dried up as the celestial show unfolded! Since not even the real Sun can dry out all things drenched in a matter of minutes, something else must have been afoot. If the 'big dry' is true, and many so claim it to be, that's got to rule out hallucinations, false images and mock suns/sundogs.
There's actually way, way more to the Fatima story than just the original visions of the three children leading up to the 'miracle of the Sun' event. For example there are the three secrets of Fatima, prophecies and visions that were given to the children by Our Lady of Fatima, a.k.a. the Virgin Mary. Unfortunately, two of the original children who witnessed the original apparition died shortly after the original events of influenza; the third went on to becoming a nun, only passing away in 2005. These prophesies, the first two released in 1941, had things to do with visions of hell; Russia and the world wars, while the third has been shrouded in controversy, is a major topic in its own right, but falls well outside the point of this essay, as does the relationship between various popes and the entire Fatima story. Needless to say that third secret may, or may not have been released by the Catholic Church depending on your bent towards conspiracy theories.
That entire chapter aside, the other interesting bit was that it was widely tipped, a prediction apparently made by 'Our Lady of Fatima' back in 1917 that there would be some sort of super-duper light show in the sky just prior to the start of another great war. Well, make of that what you will, but a super-duper aurora borealis, the likes of which hadn't been seen since 1709, took place on 25 January 1938. Hitler the of course strutted his stuff in Austria a month later and the rest, as they say, is history.
As another aside, the events were depicted in a 1952 feature film titled "The Miracle of Our Lady of Fatima". It was promoted as a factually-based treatment of the events surrounding the apparitions of Our Lady of Fatima to the three children which kick-started off the subsequent events in 1917. A more recent retelling was the 2009 film "The 13th Day."