Since I started to connect with the RPG community on the net, especially those interested in old-school gaming, I have found that the Cleric is not a very popular class. This dislike ranges from the ambivalence of James over at Grognardia to the elimination of the class in Geoffrey McKinney's Carcosa to Delta's outright glee of removing the class from his gaming. Now, I am not going to say that any of these interpretations of the game are wrong. In fact, I appreciate the fact that each of them is coming at the game from the perspective of the S&S roots of D&D. I even use James' interpretation of the class as a kind of Magic User when dealing with non-Christian/pagan priests. However, there is another perspective: the historical simulation in the war gaming roots of D&D.
I have to admit that I played my first war game before I ever heard of D&D and in my adult life have played as many hours war gaming as I have role-playing, if not more. I am also a trained historian. Thus, this aspect of the game's roots really speaks to me and I emphasize it in my games.
When looking at the game from the perspective of historic simulation, the Cleric deserves its place in the game. Not only has religion been central to every culture in human history, but Christianity has been a major factor in European history and culture since the second century. One need only look at the weapons and armor in D&D to realize that the combat being simulated is based primarily on the way war was fought in Medieval Europe, when Christianity was not only dominant, but assumed.
The spell list for Clerics in D&D reflect this historic reality — they simulate the kinds of miracles that fill Christian lore. When you believe that every Christian is the temple of God Himself, in the person of the Holy Spirit, then daily miracles are not out of place.
In terms of the classic D&D paradigm of Law vs. Chaos, Christianity has historically been equated with Law and civilization in Europe. When Rome fell, it was the Church that sheltered and protected people. It was the Church that protected the vestiges of civilization — books, scrolls, etc. — because it valued things like science, philosophy and education.
History is full of Christian adventurers. Monastics travelled the wilderness — the Biblical realm of demons — in order to take on the devil where he lives. Missionaries travelled into barbarian lands to spread the Gospel. They followed the example of the Apostles, who travelled as far as India in the east, and Britain in the west. Before them, the prophets took on all manner of ancient armies and pagan gods.
I will grant that S&S often seems incompatible, indifferent or even hostile to Christianity. Given this, the Cleric seems out of place. However, S&S itself provides the answer as to why the Cleric has a solid place in D&D — the genre blending that S&S is so comfortable with. Given that one standard fantasy trope is to tell stories of earth's distant future and given that the Church is not just a human institution, but also a divine one — "And I tell you, you are Peter, and on this rock I will build my church, and the gates of Hades will not prevail against it" (Matt. 16:18) — the Church easily fits into any world that depicts a future earth because the Church will survive into that future. Indeed, this is the model I use in my Erimia campaign.
Whether or not you use the Cleric in your games is largely up to how much you want to pay homage to the historic simulation of war games at the root of D&D. Whereas it is possible to say that I don't want Clerics in my game, it is impossible to say that Clerics don't belong at all. I hope that some of you will explore the historic simulation roots of our hobby and learn to embrace the Cleric as gleefully as I have.