Steve

The existence of God certainly is a scientific question, and atheism is a reasonable scientific conclusion. The Theist Hypothesis is that there has been supernatural interference in the natural world. All the supposed evidence for that has been satisfactorily shown to be not evidence for theism at all. Combined with the vast amount of evidence that the universe operates naturalistically, this should surely lead us to consider atheism a "theorum", to use Richard's term.

So in one short paragraph you summarize the answer already. What would be the point for scientists to belabour the point by investigating claims that are outlandishly false? (as far as religion has anything concrete to say about their Gods) It is not good for your scientific career by dwelling on things that you can't publish in respectable peer reviewed journals. :)

Edited The existence of God may or may not be a scientific question, --actually it may not be a question at all,--it depends on what you mean by 'God" and it is, as you know, quite flexible and sometimes flexible to the point of meaningless (like the gap filling God/Gods)

There is another way that theism can be investigated scientifically. It is a belief system held by humans, whose minds and psychology can be studied.

That is strictly speaking an investigation of religion or religious behaviour, not the claims of God. :)