"Believe" is a word with two denotations. One is that you actually believe something wholeheartedly. The other is that the thing you believe is your best guess. Most theists believe in their religion using the second denotation. Often, atheists seem to want to assert that theists must use the first denotation, but that they themselves are allowed the second, i.e. that they "lack a belief".
It's all well and good, but I find it rather circuitous, and I feel it is rather presumptuous when I, as a Christian, am told I have a belief and am making assertions based on that belief while they "lack a belief". After a while it comes across as purposeful obfuscation. Everyone "believes" something. That is their best guess. There's no single "neutral" belief in that sense, or "lack of belief".
That's my two cents on that.
I've never heard of that whole "two types of belief" thing, and don't think any of my friends would agree thats how they see the world, be they religious, atheist, or agnostic. Most of them hold the tack that if you believe in something, you believe in it. It's not a case of "well, this is my best guess, so i mayaswell be christian/bhuddist/jewish/etc even though i dont really believe in it." Though if thats how you roll then fair doos to you.
Personally, I dont "believe" anything that cant be proved. Theres a huge difference between believing the sun is hot, or that the sky is blue and believing in something that requires faith. One is something provable, the other by its very nature cant be proven or measured. When you're talking about theology, then there definatly is such a thing as lack of belief. I dont believe in anything, be it Gods, reincarnation, or anything of that nature. It's not a neutral belief, its an absence of belief.
Also, it seems rather hypocritical to say you take offense when people tell you that you have a belief.. and then go on to say that EVERYONE has a belief. Though i might be misunderstanding what you're upset about.