I really do not understand this idea that atheism is a "lack of belief."
You really do, as you "lack belief" in all kinds of things, which you can't actually disprove.
And the reason for your "lack of belief", is simply that you have no rational, verifiable, evidence in support of those claims - so you don't believe them.
Here are some examples: bigfoot, alien abductions, reptilian aliens, Lord Xenu the intergalactic emperor, the matrix,...
You can't disprove any of these things. You can't show any of them to not be real. Because of this, you can't actualy make the factual claim that they are NOT real - since you can't properly support that assertion either. But you most definatly will not accept the claims that they ARE real, right?
You see? You "lack belief" in LOADS of things that you can't actually show to be false or non-existant.
I lack belief in your particular religion for the exact same reason and in the exact same way.
It seems like an intellectually dishonest attempt to win a debate by refusing to engage at all
Nope.
There's nothing intellectually dishonest at pointing out that someone who makes a claim has failed to meet his burden of proof for that particular claim.
Why would you accept such a claim?
I have always thought it best to distinguish between atheism and non-theism as positions for the sake of clarity--by watering down the definition of "atheism," you're really just making the conversation more difficult.
I'ld say it becomes simpler.
You are either a theist or an atheist.
ie, you either believe a god exists or you do not.
As an atheist, I do not. What could be more simpler?
There's really nothing wrong with saying you don't believe!
I agree, but then why are you complaining about the concept of "not believing"?