[*I wrote this a few months back somewhere else]
Freud’s problem is that he did not understand the distinction between idol and icon which is detrimental to the validity of the Christian creed of belief in God. According to Jean-Luc Marion the idol is an invisible mirror reflecting the visible whereas an icon is a visible mirror reflecting the invisible. On this distinction Marion clarifies, “Whereas the idol results from the gaze that aims at it, the icon summons sight in letting the visible…be saturated little by little with the invisible.” Further, “the gaze can never rest or settle if it looks at an icon; it always must rebound upon the visible, in order to go back in it up the infinite stream of the invisible.” 
Christianity to Freud is the organized practice of wish fulfillment. He admits, “What is characteristic of illusions [belief in God] is that they are derived from human wishes.”  He elaborates, “When the growing individual finds that he is destined to remain a child for ever, that he can never do without protection against strange superior powers, he lends those powers the features belonging to the figure of his father.”  Freud has here described Christian belief as idolatry. Marion states:
The idol always marks a true and genuine experience of the divine, but for this very reason announces its limit: as an experience of the divine, starting in this way with the one who aims at it, in view of the reflex in which, through the idolatrous figure, this aim masks and marks its defection with regard to the invisible. The idol always must be read on the basis of the one whose experience of the divine takes shape there.
Contrary to this is the Christian belief that God is only knowable through creation and through Christ. Calvin explains, “His essence, indeed is incomprehensible, utterly transcending all human thought; but on each of his works his glory is engraven in characters so bright, so distinct, and so illustrious, that none, however dull and illiterate, can plead ignorance as their excuse.”  Christians also know that knowledge of God comes through the incarnate Son since it is he in whom “all the fullness of the deity lives in bodily form.” (Colossians 2:9)
One word that Freud did not understand is “transcendence”, and the word that was the aim of his idol is “reason.” The icon demands an infinite gaze, since transcendence is not a quality of man. The idol is the projection of an aim. Freud himself speaks, “There is no appeal to a court above that of reason.”  Marion explains this phenomenon among atheists:
When a philosophical thought expresses a concept of what it then names “God”, this concept functions exactly as an idol. It gives itself to be seen, but thus all the better conceals itself as the mirror where thought, invisibly, has its forward point fixed, so that the invisible finds itself, with an aim suspended by the fixed concept, disqualified and abandoned; thought freezes, and the idolatrous concept of “God” appears, where, more than God, thought judges itself.
In other words the “God” and the “idol” become one and the same, hence Freud’s misunderstanding. Also, by Freud’s sovereignty of reason his true aim is seen, that of a carved effigy in his own image given the title “reason”.
Based on this, we must be cautious of any principle taking its queue from Freudian thought, which, at the level of presuppositions, undermines the universality of principle itself and erects an idol named “reason” by which the infinite is presumably known. Finally, (alas…the point) if one were to be sly he/she would use a Freudian critique to accuse Freud of projecting his own feelings and view of reality (idolatry) upon Christianity. In viewing the world based on his own rational idolatry (he was a materialist) Freud assumed the same for Christianity, an assumption easily disproven.
 Jean-Luc Marion, God Without Being, p. 18.  Sigmund Freud, The Future Of An Illusion, p. 39.  Freud, p. 30.  Marion, pp. 27, 28.  John Calvin, Institutes of the Christian Religion, I.v.1.  Freud, p. 35.  Marion, p. 16.