If you, I, or any other atheists were to have several negative experiences with members of a group, we'd likely form negative impressions of the group from which we might generalize to other members. The nature of the group would not matter much. We could be talking about evangelical fundamentalist Christians, environmentalists, country music fans, or pretty much any group. The more negative experiences we'd had with them and the more negative each of these experiences was, the more likely we'd be to do develop negative attitudes toward the group.
Is there any reason to think that religious believers would be any different from atheists in this respect? Is it reasonable to expect that they would not develop negative attitudes toward a group no matter what kind of experiences they had with members of the group? I don't think so. In fact, I think it would be unreasonable to expect them not to be just as susceptible to this as we are.
If I'm right about this, then it is probably worthwhile to give some thought to how we behave when we interact with religious believers. I'd argue that this is especially when we are online and more prone to saying things we might not say to someone's face. Some of this has to do with modeling the values many of us claim (e.g., reason, humanism, freethought), and some of it has to do with the realization that we are often representing atheists whether we want to or not.
If religious believers are likely to form negative attitudes toward atheists or are less likely to abandon the negative attitudes they already hold toward atheists when they have negative experiences with atheists, then I am motivated not to contribute to these negative experiences. That does not mean I am going to withhold criticism of religious belief. The taboo against criticizing religious claims merely because they are based in religious beliefs has lasted far too long and caused too much harm. It is only by speaking up that we are going to abolish it.
At the same time, I think it is helpful to acknowledge that none of this gives us license to descend into hatred, name-calling, or other personal attacks when interacting with religious believers. This is a big part of why I make an effort to think before I tweet, post, etc. I do not want to contribute to the negative attitudes toward atheists which are already too common. If Christians or other religious believers are going to hate me because I am an atheist, that's on them.
