No reason justifies disbelief.

[Belacqua]

Interesting, what do you mean by 'considered' absence of belief in a god ?

I guess I want to make a distinction between, on the one hand, rocks, lizards, people raised by wolves, and people incapable of language, and on the other hand thinking people who live in a society that has religion in it. I contend that anyone raised in society will have heard the claims of religious people, and an atheist is a person who has found these claims to be unpersuasive. 

But to decide that such claims are unpersuasive means evaluating them according to some standards. 

So let's say, obviously enough, that there is no known empirical evidence for a god-like thing. For some people, this will constitute a sufficient reason -- proof, even -- that the claims of religious people are not to be accepted. That means, to me, that this results in a considered atheism: claims are heard, evaluated, and rejected for reasons. 

Now the reasons may be better or worse. A bad reason: the nuns were mean to me. A better reason: science is our most effective way to understand the world, and science seems to operate just fine without a God involved.

But to me, this means that thinking people's atheism involves these evaluative standards. The atheism of a thinking adult is not the same as the atheism of a newborn baby. And, most importantly for the point I'm making, these standards are things that can be discussed, questioned, and defended. That means the atheism may be defined as a lack, but the standards by which we evaluate claims are not lacks; they are commitments, beliefs (in the sense simply of "we hold them to be true"), etc. 

So suppose someone said he was an atheist because there is no empirical evidence. A believer might well concede there is no such evidence, but offer instead logical arguments for the existence of a God. (This is in fact how all serious theologians operate. No one after Plato has said that a God is an object known to the senses.) So, if the atheist's argument is limited to the lack of empirical evidence, he would have something to defend to his believing interlocutor. He would have to either 1) show that only empirical evidence is relevant, or 2) show that the logical arguments are false. 

My point isn't to argue the content of any of these things. Only to say that adult non-vegetable atheists can't claim that their atheism is just a nothing that has nothing to defend about it. 

And if you are a believer yourself, what standards of evidence and proof did you find convincing and why ?

In the olden days I would have said I'm an agnostic, in that I don't really know. But since sites like this are strict about saying anyone who lacks belief is an atheist, then I'm an atheist. 

But I've worked hard on the arguments of the intelligent religious thinkers, and I have not been persuaded that they have been proved wrong.