To use an analogy, it's similar to how two boxers can pummel each other in the ring, and then are able to sit down together and enjoy a peaceful diner. There is a right time and place for punching someone in the face. When two consenting people step into a boxing ring, it's the right time and place. Punching someone on the street for no reason is not the right time or place.
I see debating in a similar manner. There is a time and a place for debating. Challenging someone random on the street in a hostile manner unprovoked is not the time or place for debate. That's just being rude. On the internet however, it's a little different. Comment threads on apologist and counter apologist websites are the time and place for debate. The same goes for political websites. In fact, any time someone expresses their views publicly could warrant a debate. If I'm forced to hear your views on anything, whether it be political or religious, then you must be forced to hear my criticism. If you can't handle getting challenged, keep your views to yourself.
I welcome debate on this blog and actively seek out prospective interlocutors. I admit that I can sometimes get nasty and can appear very cocky, and if I were a theist I'd definitely think an atheist like myself would be an arrogant antitheist, to say the least. I'm conscious of this and I'm actively working to conduct myself with a certain level of politeness and courtesy, but the impersonal nature of the internet perhaps brings out the worst in me. Intellectual debates should be civil, most of the time. But as Christopher Hitchens often said, "civility is overrated." He was the kind of polemicist that I deeply admire. He could be ruthless in a verbal or written disagreement, but nice and courteous in regular social functions.
The reasons why I debate the way I do are many. I am a polemicist by nature. On both sides of my family politics and debate were regular happenings. So you could say it's in my nature. I also see debate as both a useful way to learn as well as a good way to test out arguments. On the former, debating forces you to defend certain positions, ideas and facts that you might not have come across outside of a debate format. That's an excellent way to learn new things. On the latter, if you have existing arguments, you might think they're fully sound, but your agreement with them might be causing you to to overlook a flaw that might best be discovered by someone opposed to the arguments. That's an excellent way to put an argument through the gauntlet of critique. Additionally, I also see debate as a way to change minds and I simply enjoy exploring topics I find fascinating like metaphysics, ethics, science and religion - which perhaps with some irony are the same interests that many passionate theists have.
So if you met me in person in a regular setting, you'd find me to be a nice person. I am not a hostile angry atheist in public. There's no need for that. I really do seek for a society that emphasizes love, non-violence, environmentally-friendly prosperity, and one where freedom reigns supreme. I think that secular humanism in a free and open society is the best way to achieve that. But to get society to change in the way you want it to you can do it either one of two ways. You can do it by force through political or military means, or you can do it by making the best case for your views as you can while criticizing the opposing views and hope that people will agree with you because your case sounds more reasonable than all the others. (You of course need a society that respects freedom of speech to even have this, which is why freedom of speech and expression, and freedom of the press are central to what I argue for and support.) There are many ways to debate, and some will argue that ridiculing your opponents is not the best tactic. That may be true in some cases, but I've been swayed on many an issue when I've heard it get demolished with ridicule. And so I do often, but not always, employ this in my debating style.
Now I've been called an atheist "fundamentalist" recently and accused of not being open to evidence against my atheism - as if I take my atheism on a presupposition. Nothing could be further than the truth. The problem with debating in comment threads is that we're all trying to be concise, and that means skipping detail. I cannot define every single term I use that might throw a hissy fit over semantics and I cannot cover every single nuance and exception and preempt every single rebuttal and possible misunderstanding. If I even tried to do that every comment would be an essay. So we all skip on detail and it sometimes leads to misunderstandings. I am perfectly willing to explain any part of whatever comment I make if something needs to be defined or explained further. But when I'm asked this, I'm often misconstrued as having made a contradiction or an unsupported claim. This can occur when we skip on detail and sometimes if we try and preempt this, the one thing your interlocutor finds objectionable might be the one thing you skipped on detail. And as much as I love informal debating, that makes it so frustrating.