I've just been having a couple of entertaining and actually relatively intelligent discussions with several believers on facebook, but as is so often the case a rather less reasonable individual has wedged herself in and provided an excellent example of a religious (non)argument I personally find really irritating.
The conversation began with a believer wanting to ask other christians why they felt that "the personal truths of spirituality can be proven matters of universal fact?", and at the same time to ask atheists why they "demand proof of something that cannot be proven in a physical, scientific manner?". I didn't see an answer to the question addressed to christians, but for what it's worth here's the answer I gave to the part addressed to atheists (much of which had already been said by other atheists):
"[W]hy is it that you demand proof of something that cannot be proven in a physical, scientific manner?" I'm going to answer this in three parts.
1: Science is the closest thing we have to an objective method of assessment and understanding. It's not perfect, but the scientific method has built into it as many safeguards against confirmation bias, false positives/negatives etc etc as we can reasonably manage, and study methods improve all the time.
2: As others have said, the only reason I demand evidence is that people who have these beliefs don't seem willing just to keep them to themselves and let the rest of us get on with it. If I believed there was an invisible dragon in my garage and I did nothing with that belief, imposing it on nobody, it would do no harm to anyone (except possibly me, I suppose). But if I wanted to tell other people what to do and legitimise my demands by referring them to said invisible dragon, people would have every right to demand proof that the dragon existed - particularly if some of the actions I was telling them the dragon demanded were morally abhorrent to them.
3: Your phrasing in this question betrays a trait in believers that - bluntly - I personally find intensely irritating (this is not a personal attack, it's a criticism of a particular style of religious thought). "[T]hat cannot be proven in a physical, scientific manner" is the key phrase. In recent centuries, much of what used to be attributed to gods has been shown to have natural causes. The extent of this knowledge is such at this point that it is increasingly difficult to find room for any deity within this physical universe or conforming to known physical laws... so more and more, religious people have decided their "god" exists in a different realm, or a different dimension, or is so far beyond our comprehension as humans that we cannot hope to seek him/her/it (which is always funny coming from people who reckon they know what God X thinks of gay people, for example).
Over the last few decades, "god" has morphed and changed and adapted so much that the word now has no reliable meaning; when they're telling us what to do, a christian means Jahweh as described in the bible. When they're defending their deity against rational thought, logic and science, a christian frequently resorts to an ineffable, unknowable, undetectable and inscrutable god of the fuzzy amorphous "beyond our ken" variety.
The only reason "God" cannot be proven (or disproven) by scientific methods is that the definition of "God" changes every time you look too closely at it."
There were many of perfectly sensible responses to this, but in amongst them was this (and the person she was claiming to paraphrase was ME!):
"To paraphrase...she explains that science restricts itself to natural cause. It only explains the natural world. The reason why is because the essance of science is testing ideas against the natural world, to hold constant certain variables. If there is an omnipotent force in the universe you cannot hold its actions constant. You cannot test explinations involving supernatural cause because you can't test statements about Gods actions"
And then, in a second comment:
"Lucy, this is the reason why God cannot be proven by scientific methods ^^ "
Now, I didn't even bother making the point that omnipotence is logically impossible (the ol' "microwaved burrito" argument) and I won't here, but at this point another believer - a christian I already knew from other discussions and posts in the group - weighed in with:
"Lucy, this is how one dictionary defines the Christian God (since this is what seems to be up for debate) "the incorporeal divine Principle ruling over all as eternal Spirit : infinite Mind" Incorporeal: "Not composed of matter." How can God be a spirit and still be bound by matter? How can God be eternal and still be bound by time? This doesn't make sense. God is the creator of the laws themselves, God is not bound by them. And the Bible clearly tells us that "God is a spirit" living in a spiritual dimension called "heaven." God is not bound by laws and does not dwell in this world. The reason God cannot be proven or disproven by the scientific method is because the scientific method is the study of the natural world, which God isn't a part of. We cannot hold God's actions constant. We can't scientifically study God. We can't put God in a test tube."
... and, I confess, I started to take the piss:
"I love this. In order to make room for god to exist, he/she/it's now got to have no physical mass, no physical properties, exist in a separate dimension and outside of time, and be utterly undetectable within our universe... except by people who "just feel him/her/it", conveniently. This is the perfect example of my point 3 above; carefully adapting the attributes of "god" so as to make him/her/it intrinsically invulnerable to disproof. At what point do you give up and accept that a being with no physical presence in our universe (leaving aside the "god is everywhere" thing, by the way, as well as the "made in his image" bit), no physical properties and no influence on anything we see just isn't there? (If you're struggling with this, by the way, substitute "purple jelly monster" for "god" in my second sentence, and see if it still sounds reasonable to you).
Actually, scrap that - if your argument is that god is undetectable, unknowable and incomprehensible, I'll settle for an agreement from believers to just stop telling the rest of us what to do and how to think - since you're the ones claiming god is categorically beyond our capabilities to understand."
The point I was trying to make with the title of this entry is that this is a perfect example of a religious person making two mutually exclusive arguments, failing to spot the problem and thus putting forward an argument they would never accept from a believer of any other faith (to demonstrate the spuriousness of this reasoning, I recounted a true story about a conversation I had some time ago with a "medium" who - when I tried to devise an experiment to demonstrate the validity of his belief that the spirits of dead people talked to him - presented precisely the same excuses as justification for the fact that the ghosts he claimed to talk to could not be detected by science).
This person is a christian, who believes - at a minimum - that Yeshua was the son of (and/or a part of) the god Jahweh, a deity whose opinions and demands on various topics are laid out in the bible. This person claims to know that a specific god exists, and that he has various attributes. So far, so normal... but now line that up next to the argument she's making above.
Most of the time, this person professes belief in Yahweh, with all his likes and dislikes and known "history" - and, furthermore, she professes this to be a valid belief. In the above discussion, however, she argues that "God" is systematically and intrinsically unknowable, an entity existing outside of our physical universe and beyond our comprehension. Why do I argue with these people?! This one's just told me that her own belief in the god of the Bible is invalid!
(Add to which, of course, the additional contradiction in her claim to know that an undetectable and unknowable being is there despite the fact that he's... you know, unknowable.)
Just another example of the double-think to which religious people must submit in order to maintain their faith in the face of fact...