I think it's important to temper this with respect for the person holding the beliefs, even if you don't respect the beliefs themselves.I think we can find something in between "respect" and "militancy" to use to regard our theistic fellows.
I offer not a shred of respect for theistic beliefs.
I believe them all to be delusion, often self imposed.
Like you I will smack down any theistic crap that is spewed forth around me.
I will do it brutally and with great ridicule if the moment calls for it.
I don`t however go looking for the opportunity.
However, at the same time, I think it's a bit of a lost cause to try to avoid offending everyone. Some people you encounter will be offended at the mere existence of atheists. I'm all for being respectful, but I'm my own judge of that, not the theist who might feel differently about it.