There are a lot of things we have to do as bloggers. We have to figure out what topic to blog about, write an engaging post, mix it up with readers, and be somewhat consistent with our frequency. However, we ultimately need to listen to that fat guy in the x-wing who tells us to "stay on target" even when there are tie fighters bearing down on us and we'd like to change course.
A lot of blogs fail because the blogger strays from why people came to the blog in the first place. I like to talk about writing and publishing books. I'd venture that 99% of the people who come to this blog expect that, and all of the returning readers are probably like that as well. However, were I to suddenly begin talking about other things, I'd risk losing the audience that likes this site.
There are tons of political blogs out there. Some lean left and some lean right. Almost all court controversy and encourage folks to mix it up. People go to these places because they're spoiling for a political fight. On the other hand, the mention of politics on a site that isn't about politics and never has been is a sure way to split the audience, especially in today's climate.
It's not enough nowadays to support one side or the other. No, in today's environment, you also have to define yourself by which side you oppose as well. The mere mention of a politician or political group you despise is all a lot of folks need to be whipped into a frenzy of hate and vow to crush the person who holds a differing point of view. To blog about such on a website that purports to be about writing is akin to turning off half the audience(at least), thereby alienating a large portion of your potential readers. As Michael Jordan once said when asked to explain why he wouldn't endorse Harvey Gantt for US Senate in 1990, he replied, "Republicans buy shoes too."
Religion is another area that splits people, only this topic does it even more than politics. Mention God, and an atheist will say your forcing religion into your blog. Talk about Mormonism, and a Catholic will talk about how misguided they are. Bring up the Torah, and a Muslim will say that Mohammed is God's only prophet and those who don't listen are enemies of God. Most folks react very poorly to another religion saying theirs is the only true path, and the merest hint of that on the part of the blogger can send people screaming for the hills.
There are a few other topics that will split people - sports comes to mind, especially following a painful playoff loss - but these are the main two that divide your audience. If that's your intention, then go for it. However, I want to bring together as many writers as I can on this blog and have them engage each other on the state of books and publishing. If they're always damning another person to Hell or screeching that the other side is about to bring down the country, I have a feeling that dialogue about writing might get lost in the mix.
As a blogger, part of the point is to mix things up. It's okay to be controversial...within the parameters of your subject. On a blog such as this, we should be talking about indie versus traditional publishing or why Stephanie Meyer is or isn't a talentless hack. It's good to get the juices flowing on these things because that's part of the purpose of the site, but if I accidentally mention something about Lyndon LaRouche, I don't need every political junkie in the world dropping by to yell about how they'll never read the blog again.
Talk to your readers and engage them on your main topic, but be careful where the conversation goes. This may come off as shying away from some stuff, and that's valid. For me, it's better people debate whether the stories I write are any good and how they should be improved rather than storm off in a huff because I said something religious that had nothing to do with the topic at hand.