I cannot say it better than did the great, great Isaac Asimov:
"I believe in evidence. I believe in observation, measurement, and reasoning, confirmed by independent observers. I'll believe anything, no matter how wild and ridiculous, if there is evidence for it. The wilder and more ridiculous something is, however, the firmer and more solid the evidence will have to be."
And the great, great Carl Sagan:
"Extraordinary claims require extraordinary evidence."
I subscribe fully and absolutely to these two statements.
As I have said in my spirited debates with David @electriclight, I believe every observable effect has a natural, physical cause. We may not yet understand what those physical causes are, nor what ALL the processes are that exist to cause these effects -- and Stan, this speaks to your point about scientists being amazed by new discoveries -- but there is some physical, reproducible cause for every observable effect. I simply do not buy any claim that such an effect can be caused by anything not explainable by natural processes (e.g. "God"). This is where I part ways with religious people, spiritualists, etc.
I recognize that this puts me at odds with the vast majority of human beings. I am perfectly fine with that. I would never try to foist my view upon those for whom spiritual explanations make more sense to their lives. I just ask that such folks return the favor and don't try to do the reverse. The weight of observable evidence is totally on my side, but I will never try to shove that down the throat of a spiritual person.