Thanks for the clarification.
To say...
I guess it's possible there is God but I don't see the evidence for it.
sounds a lot like agnosticism to me.
In my mind the agnostic is someone who neither confirms nor denies the existence of a god. An agnostic basically holds that there is insufficient evidence to support either position. The agnostic is open to being won over by either side but until that day arrives, is unconvinced either way.
An atheist is someone who denies the possibility of the existence of god(s). This is a belief that is held for a variety of reasons, many of which you've already pointed out. I say "belief" because the atheist believes his/her position to be true. This is worth noting for reasons we can continue to discuss. That may ultimately lead to a discussion of hermeneutics and so called objective or revealed truth subjectively perceived.
A deist believes god(s) does exist and is responsible for the cosmos, however, whoever it is or whatever it is, is not a personal god(s) that intervenes in time/history or the lives of those he/she/it has created. We've all heard the "clock maker" analogy whereby the god of the deists sets up the universe and then walks away from it leaving it to play itself out, ticking as it were, until it one day stops....or not.
A theist is obviously someone who believes that there is a god(s) and that this god(s) is a personal god(s) concerned with the well being of the cosmos and all life therein, especially sentient beings who possess a life spirit.
An anti-theist is an interesting chap indeed. The anti-theist believes that god exists and knowing, or rather believing this, sometimes sets about living in such a way that would offend or obstruct god's design for the cosmos and/or sentient beings possessing a life spirit.
These 5 groupings, in my view, sum up an important part of human cartography and the human experience.
Freeman, you mentioned:
proponents of religion advocate that human beings should live in a certain way due to their religion, so the burden is on them to prove their truth claims
It's true that proponents of some faith traditions either offer or suggest to others that their specific way of living and acting are positive, healthy ways to enrich one's life for the better. It is also true that, in some extreme cases, some proponents of some faith traditions insist that all adhere to their specific rules or belief system or else. It's much easier for me to agree with you on the second part of your statement if it's applied to this latter group.
I don't agree that there is necessarily a burden of proof placed upon those faith traditions who simply offer or suggest to others their worldview. There are many faith traditions who simply make known their central truth claims, hope and pray that others will come to know these truth claims as well, and then simply get on with living their lives. If someone comes along and desires to know more or belong then great. If not, that's perfectly ok too.
Insisting that others adhere to one's truth claims is another matter entirely. It only seems fair that a burden of proof should be placed on someone who is insisting that I accept a particular worldview with all of the ramifications of how that impacts my actions. Almost every religion throughout history as you know has, at one time or another, taken this approach with disastrous results.
It seems as if you may still identify with agnosticism more than atheism but only insomuch as you are still open to the possibility that a god exists. If that is in fact still the case, I would be interested in continuing the discussion.