One of the fundamental disagreements between theists and atheists is actually what counts as evidence. Now, if you can show that theistic belief does, in fact, lack evidential support - then you've got something.
Evidence has a dictionary definition, and you can not deviate from that. Evidence is a verifiable data/measurement.
What can count as evidence you may ask, but first let's check the dictionary definitions of "belief" in relation to "evidence", as there are more than one definition, and it is important to the topic:
#1: religious belief: belief without or in spite of evidence. Here is a quotation for you from wikipedia: "Religious beliefs, being derived from ideas that are exclusive to religion". This tells religion is based upon itself, it is a circular logic, and because the particular religion is only accepted by its members, and never any other - unlike science -, it tells "religion is nonsense".
#2: belief for a trustable person in the field explaining you the phenomena
#3: belief for personal convinction, BECAUSE YOU PERFORMED THE EXPERIMENT.
Now can come the question of evidence. Evidence is a number of collected data from which a theory can be made.
So by definition evidence is something that can be measured, and can be reproduced in the right conditions with 99.99999% accuracy (bad can happen, that's why some minor fault-margine is left in).
The evidence can come from 2 sources:
- hard facts collected
- oral evidence.
Hard facts are hard to dismiss, and are always stronger than oral evidence, will explain in a moment why.
Any theory based on the datas is only accepted if it explains at least the majority of the related datas, AND works with the least unbased assumptions (= Occam's Razor).
Eg. You can explain the world with or without a god with full consistency. We'll only accept the explanation which does not include that god, because that assumption is unnecessary.
Now the only "evidence" (in quotation-marks with reason) are oral evidence. No hard proof was ever produced.
Oral evidence always come from "humans" (I use the word in the meaning as sentient beings, but don't mind that).
What do we know of humans' talk's connection to relaity?
- we know humans can lie. Even infants lie (scientific fact). Animals lie too, but don't mind that now.
- we know that humans can have delusions.
- we know that human organs can misfunction.
- we know that the human body is accustomed to certain environment, and thus what it senses can be different from what actually happens (becasue the event is too slow, because the mind is focused to something else too much, because a recognition-pattern kicks in when it shouldn't (like at instances confusing twins).
Because all this oral evidence is far from trustable.
And we get back to the factor of trustable repeatable results.
Religion has absolutely zero trustable repeatable result despite its innumerous claims of having them. Actually the only "evidence religion can offer is how the members "feel, act, thinks or perceive."
Lastly, just to not forget, the definition of "madness:
A mental disorder, also called a mental illness or psychiatric disorder, is a mental or behavioral pattern or anomaly that causes either suffering or an impaired ability to function in ordinary life (disability)
Mental disorders are generally defined by a combination of how a person feels, acts, thinks or perceives.
Religion, because it moves away from reality, the sense of reality, IS madness, as by acting in counter of reality it inevitably causes suffering, or an impaired ability to function in ordinary life. And I won't accept madness as "social norm". I might tolerate it, but nothing else. Gravity is not "just a theory".