There are both atheists and theists who caution that it would be better for atheists not to make so much noise and not attract so much attention to themselves by speaking out against religion or theism. It's claimed that this only creates negative attention, thus encouraging distrust of and animosity towards atheists, but can't the same be said of anyone who dares disagree with the majority and dissent from conventional wisdom? How will anything change if everyone is afraid to speak out?
Opinions & Social Pressure
Most people have probably heard about the infamous Milgram experiments which reveal the extent to which people may be willing to do awful things so long as given orders from an authority figure. The influence of authorities on our actions and thinking is undeniable, but what about the influence of peer pressure? The concept of peer pressure is also well known, but how many realize the extent to which a person can be brought to deny what they know is the truth with just a little social pressure from just few others, even total strangers?
The defining experiment in this area was performed by Solomon Asch in 1955. The set up is simple enough: eight people sit together in a room and are presented with one reference line and several comparison lines with the goal of stating which of the latter group is the same length as the original reference line. One line is always the obviously correct answer, but there is also only one person who is being tested; the other seven are actors pretending to be part of the experiment. Without social pressure, subjects answered wrongly just 1% of the time; when the seven actors all gave the wrong answer, though, subjects agreed with them at least once 75% of the time.
So people don't give in to peer pressure and go along with obviously wrong answers all the time, but they do it often enough that we should be worried — yet there is cause for hope. First, these numbers show that 25% of people refused to ever be swayed by peers. Even better, if just one of the actors gives the right number, conformity to the majority (wrong) answer drops significantly. So there are always a few people who stick to their guns and refuse to believe what appears obviously wrong just because everyone is telling them they are right and, if they publicly speak out, others who doubt what the majority tells them are much less likely to continue adhering to the majority view.
The Value of the Lone Voice
Do you really need any better reason to be that person who doesn't quietly and privately dissent from majority beliefs, but who publicly, forcefully, and unapologetically dissents? There are surely a lot of people out there who may be quietly or even vocally agreeing with the majority, but who also harbor doubts that they can't shake. If it weren't for the weight of pressure from culture, tradition, family, and peers, they might dissent. Maybe what they need is to see that others do dissent and can dissent — maybe they are waiting for you. Yes, it's a shame that they need this, but why are you waiting?
Some believers insist that atheists are just trying to be rebels and atheism hasn't been rebellious for decades anyway, making atheists pretty poor rebels. They are wrong on both accounts. First, people are atheists for a variety of reasons, but believers are only projecting their own insecurities onto nonbelievers by suggesting that disbelief is due to rebellion. Second, it doesn't matter if atheism is perceived as "rebellious" or not, but the fact is that in America at least, atheism is treated as something people should be ashamed of and a reason to distrust a person.
This means that public, unapologetic atheism isn't an attempt to create an image of being rebellious, but rather an attempt to communicate the message that atheism is nothing to be ashamed of or embarrassed about. It's not a coincidence that it's believers we here this complaint from: it's their beliefs, their privileges, and their bigotry that we're challenging. They have the most to lose if disbelief reaches the point where theism is no longer privileged and treated as special, so of course they will say whatever it takes to embarrass atheists back into the closet. It's just another form of peer pressure or social pressure.
Preaching to the Choir?
Sometimes people are critical of atheists speaking out so much and argue that atheists are just "preaching to the choir," by which they mean that atheists are ultimately only talking to each other and reinforcing each others' positions rather than making a difference among others. This criticism is not only wrong, but even to the extent that it's right it's still wrong.
First, there's no reason to think that atheists are only talking to each other. Yes, atheists are reading books and blogs by atheists about atheism, but religious theists are reading them too. Atheists alone couldn't keep books by prominent atheists like Richard Dawkins on the best seller lists for so long. Whether they are being influenced or not, religious theists are listening — and it's hard to believe that none are being affected by seeing that it's acceptable to not believe in any gods, to not belong to any religion, and to be unapologetic about that.
Second, even though it's true that much of the audience for atheist books and blogs is other atheists, there's nothing wrong with that. For atheists who aren't out of the closet, it will help a lot for them to see and be inspired by atheists who are. For atheists who are out of the closet, it will help them resist social pressure to go back in. For both groups, they can benefit from seeing various arguments and ideas presented from a variety of atheistic perspectives. The more books and blogs there are out there, the easier it is to see just how diverse the atheist community is. This is good for both atheists and theists.
The only group of people this is not good for are religious apologists who are desperate to preserve religious privileges an the impression that religion is special — people who want others to realize that secular atheism is a legitimate, reasonable option. They are thus also the ones who keep trying to tell everyone how wrong it is for atheists to speak out so much.