I don't see how 'the boy who cried wolf' applies here.
Only few can understand the purpose of the story and how it applies 
Have you heard about the story of the Two Children and the messy rooms?
There are two children and both have messy rooms.
The first child sees that his room is messy and that his room would be better if it was clean. He could more easily find the things he is looking for. So he cleans his room
The second child does not clean his room until his parents threaten him with punishment if he does not, and offer him a reward if he does. So he cleans his room.
Now, out of those two children would you consider to be the better child? The one who cleans his room because he works out that it is better to have a clean room, or one that only does what he is told under threat of punishment and offer of reward?
The Religious say that Atheists have no moral and ethical ground as their morals do not stem from a higher authority, and that if that authority was removed, then we would act immorally. This is like the second child, that they only do things because a higher authority tells them to do it under threat (hell) and rewards (heaven).
Atheists are like the First Child, they work out that a society works better if people can be trusted and behave in ethical ways to each other. They have worked out that it is better to have a "clean room" (safe and functioning society) so they behave ethically because it will give them that type of society.
It appears that the Religious (based on the OP and many conversations I ahve had with religious people) think of people (and themselves) like the second child, in that they can not do anything right without coercive force (rewards and punishment).
Personally, I would like to live in a world filled with the first child as this would mean that you can really trust people. If the world was filled with people like the second child, then as long as they fear the punishment and desire the rewards it will be safe. But in a world where that authority is not feared, then because the people are like the second child they will cause chaos.
Now, that authority's instructions could then be interpreted as someone wishes. This means that a single person who does not fear the authority could conceivably distort the meaning of the authority to their own ends, and as they have no moral or ethical restrictions (as they only place their in the authority and so not consider them for themselves), then they could convince many people to behave unethically.
And this is not just idle speculation. History is replete with such scenarios, where a single person claiming communication with a higher authority leads people into unethical behaviours. There is even a psychological study done that showed how this occurs (here is a speech a TED of the Psychologist that ran the study:
http://www.ted.com/index.php/talks/philip_zimbardo_on_the_psychology_of_evil.html ).