The atheism of Marx, Nietzsche, and Freud can be called the atheism of suspicion in contrast to evidential atheism. For while the latter focuses on the truth of religious beliefs, the former inquires into their function. It asks, in other words, what motives lead to belief and what practices are compatible with and authorized by religious beliefs. The primary response of Christian philosophers should not be to refute these analyses, since they are all too often true and, moreover, very much of the same sort as found in the religion critique of Jesus and the prophets. Rather, our primary purpose should be to show the Christian community, including ourselves, how even the truth can become an instrument of self-interest. In this way the atheism of suspicion can provide helpful conceptual tools for personal and corporate self-examination.

To begin, 'atheism' comes to be used as a synonym for religious belief in a broad and inclusive sense. It includes both the atheist proper, who purports to know that God does not exist, and the agnostic who, with a kind of Socratic ignorance, only purports to know that we don't or can't know whether God exists or not.
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Following Ricoeur, who has designated Marx, Nietzsche, and Freud as the "masters" of the "school of suspicion," we can speak of the atheism of suspicion in distinction from evidential atheism. Suspicion can be distinguished from Cartesian doubt and the epistemological tradition governed by it in that Cartesian doubt in directed toward the elusiveness and opacity of things or facts, while suspicion is directed toward the evasiveness and mendacity of consciousness. Its target is not the proposition but the person who affirms it, not the belief but the believer. Its attack on the theory and practice of religion is an indirect one, whose immediate goal is to discredit the believing soul.
In other words, suspicion assumes that the task of epistemological reflection is not completed until the problem of false consciousness is met head on. ... Thereby is discovered not only the unsurpassable nature of life, but the interference of desire with intentionality, upon which desire inflicts an invincible obscurity, an ineluctable partiality. 27

But in the Introduction to The natural history of religion [David] Hume distinguishes between such questions "concerning [religion's] foundation in reason" and those "concerning its origins in human nature." ¶ This question of origin, to which the Natural history is devoted, turns out in the first instance to be a question of motive. Belief in an "invisible intelligent power" to whom prayers and sacrifices could be directed does not arrive from "speculative curiosity" or "the pure love of truth." To lead people's attention beyond the immediacy of the here and now, "they must be actuated by some passion, which prompts their thought and reflection; some motive, which urges their first inquiry." Such motives include "the anxious concern for happiness, the dread of future misery, the terror of death, the thirst of revenge, the appetite for food and other necessaries." In short, the originating motive for religious life in the hopes and fears of ordinary life, especially the latter. 27-8

... Hume is working toward a definition of idolatry or superstition--he uses the terms interchangeably--which depends more on the motivation of the believing soul than on the propositional content of belief. 28