To be an atheist you would have to go everywhere in the universe and search for god and not find him to really be sure that there is no god.
I think there is a small matter of definition to be sorted out here. I wonder how you define 'atheist', because I am almost sure that it is not the same way that dictionaries define it.
I think the proper definition is that an atheist is someone who does not believe in any gods (whereas agnostic is someone who does not know whether there are any gods). One can be both agnostic and atheist.
Now if you think it means 'someone who believes that there is no god' then you still have all your work ahead of you.
Since, presumably, you actively disbelieve in all other gods than your own I believe I have you at a disadvantage, as you need to prove a great deal more than I do.
What an interesting thought. Even if you were right about the atheist having to prove something - which you are not - somehow I have to go to the trouble of searching the whole universe to disprove something that you claim to be here and now, all the time, wherever you are.
Even if we had to prove anything, it would be sufficient to prove that God is not here, now. That in itself is no small task, but it is a lot smaller than the one you suggest.
Why do I clam this? Well, its easy. Christians claim that God set up the whole of the universe so that humans could live here on Earth and that he is omnipresent, omnipotent and omniscient. As many people have pointed out for the last thousand years or more, the big three O's are not even mutually consistent and compatible. (e.g. Can omnipotent God make a stone that is so heavy that he is unable to move it?)
So since there is no objective evidence for the existence of God here and now, and since he is a logically inconsistent being I think it is obvious that the burden of roof rests with the believer, and not the atheist.
Last week: I can't stand the idea of there being no life after death. That's why I believe in god.
Next week: I can't believe that you are so arrogant (or offensive).