Atheists Should Be Evangelistic?

I ran across this question at Daylight Atheism, and the answer given is "yes we should."

Should Atheists Evangelize?. There we read:

I have been oscillating between two sides, considering all the arguments each has to offer, and it is now time for me to take a firm stand and declare my position. I believe that atheists should evangelize, but not in the sense of bothering strangers on the street or going house-to-house and ringing doorbells. Instead, we should write letters to the editor and contribute guest editorials in newspapers and magazines. We should participate in public debates and maintain pro-atheism websites explaining ourselves to the world. We should, wherever possible, appear on TV and radio shows. We should regularly write to our elected representatives. And we should publicly take on theists practicing the more annoying forms of evangelism. By their actions, they have made themselves fair game for rebuttal; and many people no doubt would be glad to see a knowledgeable atheist confront an obnoxious streetcorner preacher. All these actions serve to spread our message and inform people of our existence without intruding directly into their lives, which is what I believe we should aim for.

Then later we read these words from Shattering Sterotypes:

The first thing I strongly recommend is that all atheists who have not already done so step forward and announce their nonbelief to friends, family and acquaintances, if their situation at all permits it. While I would not ask any atheist to speak out if there was good reason to believe that real harm would follow from doing so, atheists who remain in the closet about their nonbelief are indirectly harming not just themselves but all atheists.

Why Not?