Finally an atheist proper, with views and questions

[Belacqua]

I think a positive case can be made for atheism, such as “what would we expect to see in a universe that is governed by purely naturalistic reasons” and seeing if that is the case. Then I agree with Oppy though, there is no knock down argument that will convince everyone. And definitely nothing can be proved to mathematic certainty

Usually they say it's hard to prove a negative, so the claim "there is no god" may be difficult to finalize. And if people want to define atheism as a lack of belief, that seems reasonable to me.

As you've clearly found, though, a thoughtful adult person who is an atheist will have to deal with philosophical arguments. You have heard any number of claims by Christians, you have considered them, and you have found sufficient reason to judge them unpersuasive. No doubt you can articulate these reasons.

So to me, an atheist who is also a thoughtful adult person aware of the society he lives in will have philosophical positions that he can defend.

I mean, when you reject the claims made by Christians, I assume you do so according to good standards. These standards are your beliefs, and they can be articulated and defended. (And they may be very good standards, too.)