Authenticity of divine revelation
Theorem: It is utterly impossible to validate the authenticity of any divine revelation.
Note that this theorem does not deal with whether divine revelation exists. It only establishes that nobody can claim to have a genuine divine revelation.
 Lemma 1
Without checking the content of the message, it is impossible to distinguish between messages sent by an arbitrary Cartesian daemon and a message sent by a god.
We define a Cartesian daemon to be an (arbitrary) entity who is able to manipulate all of one's senses, dreams, and perceptions, essentially shaping the reality one perceives; or being an conscious intermediary between a person and the reality that person perceives.
There are several arguments for the possibility of existence of more than one or more of such entities given the existence of a god.
- Note that one can classify any omnipotent god being capable (the god may or may not actually do it, but such a god has such capabilities) of being a Cartesian daemon (therefore at least one Cartesian daemon exists, given the existence of a god).
- The theodicy issue, or, the problem of evil. If any omnipotent god already rid the world of evil (Assumption: misrepresenting God is an evil act) then one can assert such being cannot exist because God removed its existence already.
- The habit of people blaming some arbitrary evil entity of obscuring religious figures for the purpose of trickery/faith testing.
- Asserting that God is the only omnipotent being involves the fallacy of special pleading.
It follows that
- The method/channels a god chooses to send a message to someone can be used by any other Cartesian daemon(s).
- No foolproof authentication method can be established since the authentication key has to be sent through one of those methods/channels without the possibility of some other Cartesian daemon imitating it.
 Proof of the theorem
(This is for the monotheistic God. Proof for the case of other gods is similar)
Suppose God is trying to send a message. How would the recipient determine the message is from God? Let's suppose the message is sent by X, so the task is to determine whether X is God.
- Lemma 1 dictates that the only method to validate the message's authenticity is by checking the message's content. In this case, it is sufficient to attribute the message to God regardless the true identity of the sender.
- Suppose the content of the message is checked. How would one determine whether it is from God?
- If it lies in the realm of "God would/wouldn't say such a thing", it is compared to a separate list. In this case, since there is already a list on the receiver's end, the revelation is no longer "divine" (As in someone else have revealed it to the receiver already).
- If morality is from a single supernatural source (God in this case) there is no way such a being can authentically communicate such a standard to anyone.
- Proof: To attribute any particular moral value to come from God involves checking the moral value against some predetermined list. Since such a list already exists, it cannot possibly be revealed from God. The argument that the list originates from God suffers from the same problem of authenticity, so the chain of regress does not terminate with God.
- ↑ The idea was proposed by Descartes as an "evil daemon"
- ↑ Credit goes to Josef Balluch's feedback on alt.atheism
- ↑ In case it isn't obvious, if a certain religion allows such possibilities, it is possible that whatever God revealed to anyone can be corrupted by such entities, and thus claims of divine revelation are no longer reliable. Furthermore, any being bearing the given qualities of a Cartesian daemon is already as near to a god as makes no odds, so there is no obvious reason to believe that anything able to pass the theological Turing Test and flawlessly impersonate a god should not be regarded as a god.
- ↑ If no gods exist, there is no need to invoke such entities or this intermediate lemma, and the proof of the theorem is complete at this point.
- ↑ 5.0 5.1 For the non-omnipotent gods, notice that they usually belong to polytheistic religions/mythologies, and some of those gods have impersonation capabilities. Therefore in a similar manner any of those gods can be misrepresented, and the inability of such gods to rid the world of evil ensures the possibility of misrepresentation to occur.
- ↑ Note that mythological figures are either divinely revealed or made up by people.
- ↑ public-key cryptographic key exchanges such as Diffie–Hellman key exchange doesn't work very well since we have no way to tell whether the deity's public key is indeed from the deity in question, and we have no assurances that the Cartesian daemon cannot crack arbitrary encryption methods (see Omnipotence paradox) and simply recode the message and keys.
- ↑ In this case, the list of things one believes God would say
- ↑ Similarly, this does not address the issue of whether moral values come from God, but simply that it is invalid to claim that moral values come from God.