|Photo by Joe Mabel, via Wikimedia Commons|
At a party, you meet someone for the first time. You know nothing about her except her name and what little you can infer from her appearance and attire. She appears to be a woman of approximately your age. She looks fit, is dressed appropriately for the setting, and you find her at least somewhat attractive. But aside from her name (which she has just told you), these few observations about her appearance, and the fact that her presence at this party suggests that she probably knows someone here, you don't know anything about her. Right after she tells you her name, she informs you that she is a Christian.
If we assume that you live in the United States or another country where the overwhelming majority of the population is Christian, I'd suggest that you still don't know much more about this woman than you did before she told you she was a Christian. You don't know whether she is more or less intelligent than you did before she told you she was Christian. You don't know whether she is a morally better or worse person than you did before she told you she was Christian. She might as well have said, "I'm just like everyone else." Aside from whatever you want to make of how early in the conversation she disclosed her Christianity, you still know next to nothing about her. I suspect that most atheists would agree with this and that most Christians would not. Many Christians would be inclined to say that learning that the woman was Christian made it more likely that she was a good person.
If we were to imagine the same thing happening but change the disclosure so the woman tells you that she is an atheist, we'd find ourselves in a similar situation. Knowing that she is an atheist does not tell you that she is any more or less intelligent or any more or less moral. You still know very little about her. Again, I suspect that most atheists would agree with this but that relatively few Christians would do so. Many Christians seem to be convinced that atheists are awful people and that knowing this woman was an atheist would tell one to steer clear of her.
Aside from the one difference I've already suggested (i.e., differences in how some atheists and some Christians might react), I'd suggest that there are at least two more important differences. First, unlike the disclosure of Christianity telling us "I'm just like everyone else," you now find yourself hearing something quite different when someone tells you they are an atheist. By disclosing her atheism, this woman is indicating that she is not just like everyone else but rather different in an area most people consider extremely important. Second, by making such a disclosure to a complete stranger in a society where atheists are widely despised by the Christian majority, she's taking a real risk. Disclosures like this are often met with strong social disapproval. It might be reasonable to hypothesize, on this basis, that the woman telling you she is an atheist is somewhat of a nonconformist and a bit bolder than many people. You still don't know much about her, but it seems like you might have some clearer ideas about the sort of person she might be than you did in the first scenario.
What I am suggesting here is that the religious climate in which we find ourselves might make the disclosure of atheism more relevant and more meaningful than the disclosure of Christianity. It is the difference between indicating that one is an extreme outlier and indicating that one is "just like everyone else." Beyond that, it is the difference between linking oneself to a hated group vs. associating oneself with a group often associated with moral goodness. This difference seems largely attributable to Christian privilege and bigotry.