Well said, Popeyesays.
Not all conceptions of God share the same status of defensibility, but atheists face an uphill battle for the following reasons:
It is not for the atheist to set the agenda by defining God for the believer.
True, but when will there be any common consensus as to what God is, so that we can debate with the particular anthropomorphic characterisations of a deity in mind?
Absence of evidence is not evidence of absence. While it is altogether appropriate to demand evidence for miracles and the like, it is entirely inappropriate to demand physical evidence for God himself, who is, by definition, not physical in most religious traditions.
I will certainly agree with that, but should we keep an open mind about the existence of dragons, unicorns, elves, fairies, and so forth? What about the Flying Spaghetti Monster?
The need for a sufficient cause: the anthropic principle. Logically, something cannot emerge from that in which it is entirely absent. If human consciousness can make a conscious decision to wiggle a little finger when otherwise it would not wiggle, consciousness is manifestly of a type altogether different than matter--it transcends matter and can only be explained in non-material terms. Describing the material processes in the brain explains nothing; neither do the changes in consciousness as the result of drugs or disease illustrate the materiality of consciousness, any more than the workings of a radio explain the radio transmission. If consciousness exists at all, if it is more than a mechanistic illusion, it must, in some form that may not be readily apparent to our senses, be intrinsic to the nature of reality itself. Any claim to the contrary is extraordinary and requires extraordinary evidence.
If consciousness transcends matter, how come consciousness can only affect the biological organs that encase this consciousness? If what you are saying is true, my consciousness should be able to affect everything - from massive objects such as planets and stars, down to individual molecules, because you claim it transcends matter.
Personal experience. Unverifiability is not sufficient reason to dismiss claims of personal religious experience out of hand, much less religions long history of such claims. Neither does a description of the material processes in the brain during such peak experiences provide an explanation.
Unverifiability is a very good reason to dismiss claims of many sorts. Do you accept every conspiracy claim that you hear, that makes more elaborate explanations based off new evidences that dismisses parts of the old conspiracy claims?
As for a description of material processes affecting the brain during an experience, if we can say that a particular neurological event occurs during this unexplainable personal experience, we artificially instigate the same event, and the exact same experience occurs, surely this goes towards some sort of explanation as to how the event occured? Would it completely explain it when we found a natural instigator of this neurological phenomena?
Interpretation. Rationalism is wrong to suppose religion is first a primitive belief in something followed by the pursuit of appropriate values. It is, rather, the other way around: religion is the pursuit of values followed by interpretative concepts. If experienced values are reason to act in a certain way, it is only natural that the reason of man would then formulate a working hypotheses as to why it is so.
A debatable claim.
Religion is natural. While religion--the pursuit of values followed by conceptual interpretations serving to explain them--is normal and natural to man, it is also optional. Man does not have to be religious against his will, but the natural man, being a rational creature, craves rational explanations. (This is not to say that a nonreligious person cant be virtuous.)
Something being natural is such an overworked term that it has lost all meaning. For example, mercury can be considered natural. Not wearing any clothes can be considered natural. Conversely, discoveries like pennecillin and computers can be considered "unnatural". Why should something being "natural", and other things not being natural change our consideration of an object or an idea?