Both Feuerbach and Freud accordingly felt that it was high time that the human race shake off these infantile illusions and come to grips with reality as it is
One of the classical demonstrations of God's existence is the so-called argument from desire. It can be stated in a very succinct manner as follows. Every innate or natural desire corresponds to some objective state of affairs that fulfills it. Now we all have an innate or natural desire for ultimate fulfillment, ultimate joy, which nothing in this world can possibly satisfy. Therefore there must exist objectively a supernatural condition that grounds perfect fulfillment and happiness, which people generally refer to as "God."
I have found in my work as an apologist and evangelist that this demonstration, even more than the cosmological arguments, tends to be dismissed out of hand by skeptics. They observe, mockingly, that wishing something doesn't make it so, and they are eager to specify that remark with examples: I may want to have a billion dollars, but the wish doesn't make the money appear; I wish I could fly, but my desire doesn't prove that I have wings, etc. This rather cavalier rejection of a venerable demonstration is a consequence, I believe, of the pervasive influence of Ludwig Feuerbach and Sigmund Freud, both of whom opined that religion amounts to a pathetic project of wish-fulfillment. Since we want perfect justice and wisdom so badly, and since the world cannot possibly provide those goods, we invent a fantasy world in which they obtain. Both Feuerbach and Freud accordingly felt that it was high time that the human race shake off these infantile illusions and come to grips with reality as it is. In Feuerbach's famous phrase: "The no to God is the yes to man." The same idea is contained implicitly in the aphorism of Feuerbach's best-known disciple, Karl Marx: "Religion is the opiate of the masses."
In the wake of this criticism, can the argument from desire still stand? I think it can, but we have to probe a bit behind its deceptively simple surface if we are to grasp its cogency. The first premise of the demonstration hinges on a distinction between natural or innate desires and desires of a more artificial or contrived variety. Examples of the first type include the desire for food, for sex, for companionship, for beauty, and for knowledge; while examples of second type include the longing for a fashionable suit of clothes, for a fast car, for Shangri-La, or to fly through the air like a bird. Precisely because desires of the second category are externally motivated or psychologically contrived, they don't prove anything regarding the objective existence of their objects: some of them exist and some of them don't. But desires of the first type do indeed correspond to, and infallibly indicate, the existence of the states of affairs that will fulfill them: hunger points to the objective existence of food, thirst to the objective existence of drink, sexual longing to the objective existence of the sexual act, etc. And this is much more than a set of correspondences that simply happen to be the case; the correlation is born of the real participation of the desire in its object. The phenomenon of hunger is unthinkable apart from food, since the stomach is "built" for food; the phenomenon of sexual desire is unthinkable apart from the reality of sex, since the dynamics of that desire are ordered toward the sexual act. By its very structure, the mind already participates in truth.
So what kind of desire is the desire for perfect fulfillment? Since it cannot be met by any value within the world, it must be a longing for truth, goodness, beauty, and being in their properly unconditioned form. But the unconditioned, by definition, must transcend any limit that we might set to it. It cannot, therefore, be merely subjective, for such a characterization would render it not truly unconditioned. And this gives the lie to any attempt--Feuerbachian, Freudian, Marxist or otherwise--to write off the object of this desire as a wish-fulfilling fantasy, as a projection of subjectivity. In a word, the longing for God participates in God, much as hunger participates in food. And thus, precisely in the measure that the desire under consideration is an innate and natural desire, it does indeed prove the existence of its proper object.
One of the best proponents of this argument in the last century was C.S. Lewis. In point of fact, Lewis made it the cornerstone of his religious philosophy and the still-point around which much of his fiction turned. What particularly intrigued Lewis was the sweetly awful quality of this desire for something that can never find its fulfillment in any worldly reality, a desire that, at the same time, frustrates and fascinates us. This unique ache of the soul he called "joy." In the Narnia stories, Aslan the lion stands for the object of this desire for the unconditioned. When the good mare Hwin confronts the lion for the first time, she says, "Please, you are so beautiful. You may eat me if you like. I would sooner be eaten by you than fed by anyone else." To understand the meaning of that utterance is to grasp the point of the argument from desire.
Bishop Robert Barron is the founder of the global ministry, Word on Fire, and is an Auxiliary Bishop in the Archdiocese of Los Angeles.