Getting back to the "cognitive bias" part, I think we have established that religious groups can:
a) Rejects another group because it doesn't understand that group, even though the other group has never committed an offence against them
b) Do not reject their own members, even though they commit the offences that they attribute to the out-group.
This is a cognitive bias - seeing the world in a way that does not reflect reality.
While this can certainly be true of religious groups it can also be true of any other grouping of humans that has existed or will exist. They have even shown a similar phenomena in completely random groups separated only by
t-shirt color.
What you have identified is referred to by psychologist as in-group favoritism.
https://en.m.wikipedia.org/wiki/In-group_favoritismThe two main theories regarding the cause of this are referred to as Realistic Conflict Theory and Social Identity Theory. In-group favoritism is essentially one of humanities built in flaws.
Religious organizations are made up of humans and thus not immune to humanities inherent flaws.
This makes judging people based on group status a flawed method to interpret the world. In this case, the idea that "atheists do not publicise their moral code and therefore cannot be trusted" can be seen as just as flawed, since this viewpoint would also apply to any out-group.
So, getting back to your original point --
It is reasonable to be suspicious of the values and morals of someone operating with no moral code. It is also reasonable to be suspicious of someone who knows and can anticipate your moral code but refuses to disclose his own. I fail to see the cognative bias.
is not useful information, since the religious person will be more suspicious of
any out-group, regardless of the god (or lack of god) they follow.
I don't think any of these points come close to dismissing my original point, which is
It's more likely that religious people need religion in order to be moral actors, just as BADecker wrote.