In etymology, Christians are all cretins. The original cretins were deformed and mentally deficient dwarves found in remote valleys in the Alps. In modern-day science, their condition is called congenital iodine deficiency syndrome, but the Swiss didn’t know about that back then. All they knew was that these people, while different in appearance, were still human and Christians. So, they began to call them Cretins, which means Christians.
The Swiss meant no ill behavior calling these different humans cretins. But the word became misused by bullies and soon became a derogatory word.
The first idiots were also Christian, or perhaps the first Christians were idiots. The word idiot appeared in English in the Wycliffite Bible of 1382. In the Book of Deeds (we call them the Acts) states:
Forosoth thei seynge the stedfastnesse of Petre and John, founden that thei weren men with oute lettris, and idiotis
Then, a verse in the King James Version:
Now when they saw the boldness of Peter and John, and perceived that they were unlearned and ignorant men
But, in the Latin of Saint Jerome, the verse went:
videntes autem Petri constantiam et Iohannis conperto quad himines essent sine litteris et idiotae
Saint Peter and John were idiots because they were laymen. They were their own men than belonging to some professional class. If they had spoken their own language, they would have become an idiom. If they had their own way of doing things, like eccentrics, they would have been idiosyncratic.
The words cretin and idiot were never meant to be an insult, one being a compliment and the other a description. But, life is cruel and unfair and without the cruel world we would have no word for idiot or cretin.
The word moron was misinterpreted in 1910. At this time, the word was invented by the American Association for the Study of the Feeble-Minded. They took the Greek word moros meaning dull or foolish, and used it to refer to those with an IQ between 50 and 70. The word was suppose to be used only by doctors and diagnosis. In seven years from its creation, the word escaped into the cruel world and is now an insult.
What’s even crueler is when your name turns into an insult. This happened to John Duns Scotus (1265-1308). He was a theologian and thinker of his day, and perhaps the greatest (depends who you talk to). He drew the finest distinctions between different ideas, and linguistically speaking, became his downfall.
When Duns Scotus died his followers and disciples continued his work. They were eventually called Duns-men. During the Enlightenment period, people became humanists and were angry at these Duns-men as they tried to contradict the Aristotelian enthymeme (a three-part argument used by Aristotle). They became the enemies of progress who would bring back the Dark Ages. Thus, Duns-men became dunce.