The most I will do, usually, is just explain my reasoning for not considering myself one.
I have a conviction that the will to believe or disbelieve is one which is much, much deeper than intellectual argumentation. Some don't believe that, but I do.
At one point in my life I've been on either side of the fence in the God debate. My brief bout of atheism was brief because it was a violent reaction against the form of theism I was raised in, which formed the basis of my religious ideas at the time. (That form of theism no longer serves as the bedrock for my belief system.)
I have atheist friends and we get along fine. I respect their beliefs, am challenged by some of their more searching problems with religion (although I think most of them rely too much on cliches and stereotypes), and am pained to add that they don't seem quite so kindly turned towards my beliefs. In fact, I find the most dyed-in-the-wool atheists to be every bit as evangelistic and condescending as the fundamentalist religious believer.
There is in my thinking no room for an idea of God which has it that there is a single way to believe; that if one is unable to "find the right path" that person will damned eternally because of that inability. I have no patience with forms of religion that divides humanity and encourage hate.
There is another aspect of the way I think. I seriously doubt we humans are as smart as we think we are. Doubt is an ever present element of my thought processes. I'm reconciled to the fact that my best thinking may be in error, and I'm fine with that.
That being the case, why would I undertake to argue with atheists or, for that matter, any hidebound believer in a system of thought?
Atheism holds no fear for me. My favorite kind of atheists, however, are those who are also committed humanists. And with that variety of atheist I am more than willing to link arms and walk. So should any believer in liberal spirituality.
There may be more to existence than meets the eye and again there may not. Either way, that the human family is one should be obvious to all. I really don't enjoy arguing with my brothers and sisters.