The blogospheres involving science, science journalism, religious apologists, denialists, and atheism have been having a war on tone and civility as of late. There are literally dozens of posts on the subject. For example, at ScienceBlogs, there has been a strong and mixed reaction to an essay by Virginia Heffernan that is critical of the tone of many of the blogs on that site. You can go to ScienceBlogs and due a search on Heffernan and read all of the various reactions to her essay.
There has also been a sort of war between what are being called the "New Atheists" vs. the what? I don't know what they call themselves. Old Atheists? The New Atheists include the likes of Christopher Hitchens, Richard Dawkins, and PZ Myers. The accusation by the "others," for lack of a better term, is that they are somewhat "militant" in their tone. They attack the opposition and resort to name calling or ad hominem arguments. If you go back and look at some of my posts on Westboro or the Dove World folks, I do the same things. I believe I was even called "strident."
I think that different tones are required and justified based not only on the target audience, but also on the target of the post. Here is my take on it. I will generally fall into a more strident, vulgar tone, when the target of the post is so lacking in their ability to understand logic and reason, that anger, laughter, and humiliation are the only real avenues for expressing my discontent. If I had the opportunity to actually sit down with the target of one of these posts, and assuming that I was fully capable in forming ironclad arguments lacking any logical fallacies, was able to demonstrate ample evidence, and could maintain a civil tone, it would not do one bit of good in even hoping to begin to change that persons mind about their beliefs. They are simply unable to understand the logic and reason. And, when I believe the audience for said post would find the position of the post's target to be utterly and completely lacking of logic and reason, then I have no problems falling into a more strident tone. Basically, there is no real educational opportunity to be had in that case. Also, if someone "on the fence" happens to read such a post, I would hope they would see the absurdity in the target's position and based on the tone of the post, come to realize the idiocy of the target itself.
For some of my other posts, such as the atheism vs. Atheism post, I am making an effort to educate, so I hope that my tone and style comes across more friendly. I try to build up the argument using examples and avoid the use of ad hominem arguments.
So, I hope that better explains why a post may come across one way versus another. I am conscious of the choice I make with respect to tone and civility.