Deus vult is Latin for "God wills it". Deus Vult was the battle cry of the crusaders. Use of the term implies that another crusade is necessary. Saracen is an associated term and was used by medieval Europeans to refer to Muslims, particularly Muslims in former Roman provinces. It's a pretty good sign you've stumbled upon an internet tough guy or an alt-lighter attempting to use it in a memetic fashion to hide its racist intentions.This term may be a bit less trustworthy than others, and it may just be that you've met with an internet historian making a joke. Or both.
Deus lo vult ("God wills it", "vulgar" form of Latin Deus vult; variants Deus le volt, Dieux el volt; Deus id vult, Deus hoc vult, etc.) is a Catholic motto associated with the Crusades, more specifically with the Princes' Crusade of 1096–1099. The phrase appears in the Vulgate translation of the Christian Bible.
- manuscripts of Gesta Francorum variously have Deus le volt, Deus lo vult, as well as the "corrected" forms Deus hoc vult and Deus vult. Winter (1890) cites Barth: "Barbaro-latina vulgi exclamatio vel et tessera est. Videri autem hinc potest, tum idiotismum Francicum propiorem adhuc fuisse latine matrici". Winter (1890) comments that the presence of the Romance article (lo, le) was very likely part of the original motto as shouted in Amalfi, as both the author of Gesta Francorum and that of Historia Belli Sacri report it.
- Mrs. William Busk, Mediaeval Popes, Emperors, Kings, and Crusaders, Or, Germany, Italy, and Palestine, from A.D. 1125 to A.D. 1268, Volume 1 (1854), 15, 396.
- Template:Cite book
Deus Vult (Classical Latin for "God wills it") was the cry of the people at the declaration of the First Crusade by Pope Urban II at the Council of Clermont in 1095 when the Eastern Orthodox Church requested help in defense from the Seljuk invasion of Anatolia.
- [Source: Morwood, J: A Dictionary of Latin Words and Phrases, page 46. Oxford University Press, 1998]
The First Crusade arose after a call to arms in a 1095 sermon by Pope Urban II. Urban urged military support for the Byzantine Empire and its Emperor, Alexios I, who needed reinforcements for his conflict with westward migrating Turks in Anatolia.
- [Source: Lock, Peter (2006). Routledge Companion to the Crusades. Routledge.]
As you have asked in your question, which showed no sources as to Deus Vult being used recently, (don't worry I got you covered), it is indeed gained use, which I will prove in just a moment.
Crusader Kings has been out for a good while (3 years) so the current surge in its use has nothing to do with the game. Perhaps it helped popularize the phrase, but other than that it has nothing to do with CK2.
Here are a few examples of this phrase being used: (I apologize as in some of these you might have to scroll down a bit)
Control+f. As you can see, there is a lot of use for this phrase here. Let's look at what the people say along with it.
"we're long overdue for another crusade"
"Time to remove kebab"
"And centuries later, their descendants gave Europe away for nothing so they wouldn't be called racists. The End"
"DEUS VULT! must remove the kababs!!!"
"We will never let our Europe turn into 3rd world shithole! We will never accept Sharia Law! CRUSADE NOW!! DEUS LO VULT!!!!"
"IT'S TIME FOR A NEW CRUSADE, DEUS VULT"
"Muslims have always been self proclaimed victims. Killing innocent christians for hundreds of years and when finally the pope calls upon people to finally put an end to it, they bitch and moan to this day they blame us, even now muslims will kill thousands and still say christianity is still dangerous"
"As an atheist, I would gladly go on a Crusade with my Christian brothers to get rid of this Islamic plague. DEUS VULT!"
"IT IS TIME TO BRING BACK THE CRUSADES. GOD BLESS YOU ALL IN THIS DARK TIME. USA."
"RIP FRANCE, RIP ENGLAND overflowed with muslims"
"I think its about time we went on another crusade."
"A new order of Knights Templar is needed once again to fight the Islamic hordes plaguing western civilization."
Whether or not that sounds like its said in context of CK2 is up to you. You can look for Deus Vult being used in other places in much the same way to refer to anti-islamic beliefs. For example voat (Google deus vult:voat) The current surge of Deus Vult does not seem to be part of CK2, but part of a growing hatred for islamification, proved by simply reading the comments that come with that phrase.
It is used essentially as the christian version of the meme "Remove Kebab".
"Deus Vult" (“God wills it” in Latin) was a battle cry called out by Crusaders at the declaration of the First Crusade in 1095. Online, the historical phrase has gained popularity among fans of the strategy video game series Crusader Kings, as well as the alt-right camp on Reddit's /r/The_Donald and 4chan's /pol/ (politically incorrect) board, typically in the context of discussions relating to Islamic extremism and the moe anthropomorphized humanization character Christ-chan. The phrase can be seen as the Christian equivalent of "Allahu Akhbar", an Islamic Arabic expression that is most well-known as the battle cry of Jihadhists in Western cultures.