Some atheists like to use the analogy of religion being like a "crutch.". Dr. David Eller suggests, below, that this is a poor analogy. In my own, limited experience, his words ring true.
Like a pair of glasses, humans see with culture, but they do not usually see culture. Computers do not know they are running a program; they simply follow instructions. Seeing your glasses, recognizing your program, is a rare thing, achieved by few individuals in even fewer societies. It demands a certain amount of "freedom," a certain amount of distance from oneself. It is also probably not an entirely desirable or beneficial ability: taken-for-grantedness is adaptive in a strong sense. The very opaqueness and "obviousness". . . of the human world spares us from having to remake the same conclusions and judgments over and over; as some anthropologists and sociologists have emphasized, culture provides us with a set of "frames" or "scenarios" with familiar and predictable patterns and outcomes. These frames or scenarios get the average person through the average life with little uncertainty and little remainder, but only so long as the conditions in which they were forged persist.
Some atheists and other critics of religion like to use the analogy of a crutch for religion -- that it is something that the weak use to get them through otherwise difficult situations. The implication is that, if they were stronger (like us) they could dispense with the crutch and walk independent and free. [But] you cannot pull a crutch from underneath a cripple and expect him or her to walk. Rather, they will fall and then probably blame you for the accident. The real point is more profound but perhaps more discouraging: religion for the religious person is like culture for the cultural person -- it is the glasses, not crutches. And these glasses are not prophylactic -- they do not help the person to see "better." They make seeing at all possible. Maybe an ultimate analogy for culture in general and religion in particular is not glasses but the very eyes themselves. You could not expect to pull someone's eyes out and have them see better, any more than you could expect to take away someone's culture and have them understand and act better.
-- David Eller