Agnosticism is the only scientifically passable position. There is no known experiment to test whether the God of Abraham, Zeus, Thor, Horus, Mithra, Odin, Bael, Vishnu, Satan, Kwan Yin, Pan, Allah, or Enki exist, so any answer other than "I don't know" is probably an assumption. I'm open to the possibility that someone, somewhere has opened contact with higher beings, but until this is personally demonstrated I will remain agnostic to these entities...
Atheism is not necessarily any more scientific than theism. It may be more-so than specific paths in particular, especially the Abrahamic paths, because the god of Christianity and Islam is comprised of so many fallacies and mutually incompatible properties that the proposition essentially kills itself under any close scrutiny. But for the most part, while atheism relies on a "probably not true" as opposed to a "probably true" gut feeling, at the end of the day neither side is actually applying the scientific method.
I myself am a pantheist, and revere Nature as a godlike organism. Since I have made Nature herself as my point of focus, I don't feel any real need to prove that my deity exists.