Greta Christina has a post on what I literally find the least interesting topic kicked around in atheist circles, the question of whether or not atheists should be "angry" or "friendly". There's many variations of this argument, with some of the hardline friendly types suggesting that there's never any value to mocking religious beliefs, no matter how humorous they are, and hardline angry types minimizing some of the differences between some of the more liberal religious sorts and the fundies. (I actually have a lot of respect for this, because it's a nice corrective to liberal Christians exaggerating the differences.) I'm linking Greta because she's got the only response to this that makes sense, which is basically "aw, fuck it, do what makes sense to you". I've said this before, but it's worth repeating: when it comes to the promotion of any worldview or set of values, you need all sorts, barnstormers and pleasers, jokesters and earnest sorts. Different styles make sense to different people, and the more diversity in your movement, the more ears you get. Riot Grrrls captured the imagination of would-be feminists who weren't so much into the power suits-style feminism or the hippie-feminism of the 70s, and that's a good thing.
But I also reject the discussion because it's based on a false proposition, that there's a "right" way to persuade, some formula that will get people who aren't into your message to start listening. This is a widespread delusion that spreads far beyond the atheist movement—it's part of the illusion of control—and I think it owes a lot to cultural paranoia about how advertisers and marketers manipulate us. Well, they certainly intend to and they're often quite powerful at it, but it's important to realize that what any given message means is about 70% what the audience brings to it, and about 30% what the messager does, and that's if you're being unbelievably generous to the messenger. Truly effective manipulation works with this limitation. When manipulation works, it's about affecting an immediate behavioral choice, and it addresses already existing desires and beliefs to do so. And even then, the most effective manipulations get say, 10-30% of people. (Here's a good example. Notice that it really only worked in influencing behaviors within a few hours, and it required tapping pre-existing beliefs to do so.) There's no reason to believe that what advertisers do, which is to push pre-existing buttons to get impulsive decision-making, can be compared in a meaningful sense to what movements are doing, which is trying to change minds.
Which isn't to say I think we should give up. Historically, movements do have a good track record of changing minds. But if you look at them honestly, you'll realize they did so in part by throwing all sorts of shit on the wall and seeing what sticks. It also depends on cultural context. Movements take off in no small part because the culture around them shifts, making a larger percentage of the population open to their arguments. Atheism shouldn't be any different in this regard.
I think it would do the atheist movement well to remember that 95% of people who see a book titled "The God Delusion" and who pick it up are willng to be persuaded. I definitely see that many atheists get this, since the discussions about growing the movement center around the assumption that people out there are asking questions. But I don't see a lot of people making the important leap from there, which is realizing that because people who come to you are looking not to believe, how you present your message is just not that important. At this point, people asking questions are just going to have a variety of tastes, and so the main thing is having a lot of variety in messaging so that different people can find the opening that makes the most sense to them. But one thing I think is probably not worth our time too much is asking, "What does religion offer that we can replicate so that people who are deep into religion can be persuaded?" I myself have asked this question, and now I really realize that it's bunk. What religion offers is that it's what you've always had. People tend to de-convert for two reasons: 1) their religions are so alienating they ran off or 2) they found themselves in a community where belief in the supernatural wasn't a prerequisite to get along with others, and so their need to believe faded away, making them open to atheist arguments. Neither of these are within our control, though perhaps atheists would be wise to take a long view into investing more resources to grow communities where people stop feeling so much pressure to be religious.
And completely off-topic, but I think worth considering is the distressing anti-satire critique that has formed on the left. Anti-satire critique goes something like this: "Since some people who see a satirical send-up of their worldview will actually read it like an affirmation, satire is dangerous." They usually cite the fact that many conservatives watch Stephen Colbert and believe him to be one of theirs for real. This is again the illusion of control, and the false assumption that there's a message that can be crafted where the messenger has much more control over what the audience perceives. What they fail to understand is that the counter-strategy to satire and irony, which is more earnest messaging, also misfires with a huge percentage of the audience. A lot of people, like myself, have such an instinctual hatred of earnest pleading that the message behind it automatically becomes more suspicious because the messenger is hammering at it. More importantly, what the audience brings to a message is exponentially more important than what the messenger brings. The same conservatives who've convinced themselves that Colbert is one of theirs, if presented with a more earnest version of the same liberal messages, would roll their eyes and shut off the TV, making fun of how stupid and earnest liberals are. There's really no way to construct a message that will reach a hostile audience in the way that you hope it will. The best you can do is keep talking and hope that people who are coming around find your particular style to be what they need to make the leap.