John Adams Calls Christianity "the most bloody religion that ever existed":

Yes, he did, in this letter here to F. A. VANDERKEMP, 27 December, 1816. However it helps to read his entire thoughts in context. Adams' thoughts on Christianity were qualified in a half full half empty sense. Adams thought Christianity was both the best and worst religion in the world. And he believed this in large part, because, he thought himself a "Christian" (though one who disbelieved in original sin, trinity, incarnation, atonement, eternal damnation and infallibility of the Bible).

The following is the ENTIRE letter, so readers can examine the context in full:

I do declare that I can write Greek better than you do, though I cannot say, so well as you can if you will. I can make nothing but pothooks and trammels of the frontispiece of your amiable letter of the 15th. If you had quoted your authority, I might have found it.

Jesus is benevolence personified, an example for all men. Dupuis has made no alteration in my opinions of the Christian religion, in its primitive purity and simplicity, which I have entertained for more than sixty years. It is the religion of reason, equity, and love; it is the religion of the head and of the heart.

It would be idle for me to write observations upon Dupuis. I must fill thirteen volumes. If I was twenty-five years old, and had the necessary books and leisure, I would write an answer to Dupuis; but when, or where, or how should I get it printed? Dupuis can be answered, to the honor and advantage of the Christian religion as I understand it. To this end I must study astrology as well as astronomy, Hebrew, Greek, Latin, Arabic, Persian, and Sanscrit.

But to leave Dupuis to be answered or reviewed in Edinburgh or London, I must inquire into the attributes given by the ancient nations to their divinities; gods with stars and new moons in their foreheads or on their shoulders; gods with heads of dogs, horns of oxen, bulls, cows, calves, rams, sheep, or lambs; gods with the bodies of horses; gods with the tails of fishes; gods with the tails of dragons and serpents; gods with the feet of goats. The bull of Mithra; the dog of Anubis; the serpent of Esculapius!!!!

Is man the most irrational beast of the forest? Never did bullock, or sheep, or snake imagine himself a god. What, then, can all this wild theory mean? Can it be any thing but allegory founded in astrology? Your Manilius would inform you as well as Dupuis.

The Hebrew unity of Jehovah, the prohibition of all similitudes, appears to me the greatest wonder of antiquity. How could that nation preserve its creed among the monstrous theologies of all the other nations of the earth? Revelation, you will say, and especial Providence; and I will not contradict you, for I cannot say with Dupuis that a revelation is impossible or improbable.

Christianity, you will say, was a fresh revelation. I will not deny this. As I understand the Christian religion, it was, and is, a revelation. But how has it happened that millions of fables, tales, legends, have been blended with both Jewish and Christian revelation that have made them the most bloody religion that ever existed? How has it happened that all the fine arts, architecture, painting, sculpture, statuary, music, poetry, and oratory, have been prostituted, from the creation of the world, to the sordid and detestable purposes of superstition and fraud?

The eighteenth century had the honor to discover that Ocellus of Lucania, Timæus of Locris, Aristotle, Tacitus, Quintilian, and Pliny, were in the right. The philosophy of Frederic, Catharine, Buffon, De la Lande, Diderot, d’Alembert, Condorcet, d’Holbach, and Dupuis, appears to me to be no more nor less than the philosophy of those ancient men of science and letters, whose speculations came principally from India, Egypt, Chaldea, and Phœnicia. A consolatory discovery, to be sure! Let it once be revealed or demonstrated that there is no future state, and my advice to every man, woman, and child would be, as our existence would be in our own power, to take opium. For, I am certain, there is nothing in this world worth living for but hope, and every hope will fail us, if the last hope, that of a future state, is extinguished.

I know how to sympathize with a wounded leg, having been laid up with one for two or three months, and I have felt the delightful attentions of a daughter. May you have the felicity to celebrate as many more lustres of Madam Vanderkemp as human nature can bear.