Science is only what can be observed.

That is the first time I've seen that wacky notion expressed here. Science cheerfully and openly expresses its shortcomings and gaps in knowledge. Science acknowledges that certain phenomena have yet to be properly observed because we have yet to develop the means to properly observe them. Science accepts that theories have to be under constant review as new knowledge comes to light. Good science knows no dogma. Dogma is the enemy of good science. Wow, Jack. Doesn't all that make your little sentence above look so dismal. It's a good job you don't actually think it. And neither does anyone else.

I can proudly use Science as an ally to support my atheistic arguments.

You do not "use" science to support anything. Science is neutral. What you do is to subject assertions made to you to the rigour of science. Now whilst science acknowledges its own gaps (see above), it is still perfectly valid to check assertions made to you against the bar of evidence. It can be quite a high bar. Your assertion may not satisfy every demand of evidence but it may do so sufficiently to be allowed as a hypothesis or theory. Those two words simply express notions that are of interest to science because, at least in part, until further evidence comes to light, they can yield to exploration via the scientific method. All good stuff. But it is possible to make an assertion that can never yield to scientific enquiry. The existence of God is one such. He is defined in such a way as to be not only outside the laws of nature but also to be beyond investigation. Now this is quite a serious matter. It doesn't take the average scientist long to accept that there isn't much point pursuing the existence of God as a scientific project. Do you see? Science at this juncture has parted company with God. They don't even connect tangentially. They can't communicate. You can't use science either to prove or disprove God because the two simply don't see each other.

Now my problem as an atheist is, who actually defined God in that way? Was it people? Or did someone come down to primitive Man in a chariot of fire and permanently imbue him with the God notion? I'm a little suspicious that God was deliberately designed to be both above all natural laws and inaccessible. A God of that kind can never be challenged. His truth cannot be undermined. Those tenets are enshrined in the major religions. Further embellishments to the story turn God into someone who intervenes and who can be quite authoritarian. That is also rather useful to big religion. So my suspicions stack up. I turn back to the only rational means I know, the scientific method, to assess all the evidence. And find it wanting. Absent, in fact. That's what makes an atheist an atheist. Note that at no time do I say that God does not exist.