Myth:
Atheism acts as a crutch. It gives folks a prepackaged worldview and saves them from having to think for themselves or to seek answers to or even ask life's difficult questions. Atheism is the opiate of the egotistical.
Response:
It's not uncommon for atheists to argue that religion and theism are a sort of crutch that makes it easier for people to deal with problems in life, so perhaps it's not a surprise that some might try to turn this around and argue that atheism is actually the crutch. How, though, can mere disbelief in gods act like a crutch in any manner — no matter how metaphorical? The problem lies in misrepresenting atheism as if it were a belief system. If that were true, it might theoretically be possible to think that atheism does the things described — but from a false premise, false conclusions quickly follow.
Is the absence of belief in elves a crutch? Is disbelief in fairies a crutch? Christians don't believe in Zeus or Odin, but are those crutches? Is it a crutch that I don't think that Elvis is alive and living in a trailer park in Arkansas? Of course not — none of these can be called crutches in any meaningful way and the same is true of disbelief in or the rejection of gods. There are millions of things people don't believe in and they can't be called crutches by those people who do believe in them.
People who promulgate this myth are trying to shift the burden of proof to atheists by making them justify their atheism. In reality, the burden of proof or support is on theists and unless they can show sufficient justification for their beliefs, then disbelief is the default. We are all born without belief in gods and most people live their lives without believing in most gods. If someone wants others to make an exception for one or two at some point, the burden is entirely theirs to show why.
As noted above, the fundamental error being committed here is treating atheism as if it were a belief system — that's what allows one to say that it's a "prepackaged worldview." But what worldview, prepackaged or not, is shared by all atheists, regardless of whether they are humanists, Objectivists, existentialists, communists, Raelians, Buddhists, Taoists, Scientologists, or anything else? The answer, of course, is "none" because atheism isn't an ideology and doesn't provide a worldview to anyone. It is, instead, a single data point which may or may not be incorporated into a wide variety of worldviews — just like theism.
Thus we find that reality is exactly the opposite of what myth portrays: atheism doesn't create any "prepackaged worldview," but precisely this is true of religions which tell people who they are, what their role is in the universe, how to behave, and how everything will turn out. Anyone who grows up in such an environment but leaves it behind must do exactly the opposite of what the myth claims about atheists: they will have to think for themselves, seek answers to difficult issues, and address life's most difficult questions — not so much because they are atheists, but because they can no longer simply accept the answers that had previously been provided by religion. Freethought isn't exclusively atheistic, but there's a reason why freethinkers are more likely to be atheists than theists.
If we step back and look at the myth as a whole, we find that it looks suspiciously like an attempt to pack together as many atheistic criticisms of religion and launch them back at the atheists: it's a crutch, it's a prepackaged worldview, it helps people avoid difficult questions, it's an opiate. It's arguable that anyone who tries to spread such a myth isn't doing so because they find these claims plausible; instead, it seems more likely that they only developed the claims in order to find some way to attack atheists in a manner that they find atheists attacking religion. It's a classic example of trying to match one's position to their desires rather than according to an honest, fair appraisal of reality.
