Absence of Evidence is Not Evidence of Absence?
A common retort of theists when their faith in God is challenged is to resort to witty-sounding aphorisms. One common saying which arises when an atheist brings up the lack of proof for God is, "Absence of evidence is not evidence of absence."
This is of course completely true. However, a lack of evidence very clearly indicates that the hypothesis that God exists should be rejected, because the burden of proof is on he who makes the claim that God exists.
Some theists twist this around, citing some extreme atheists who assert that God does not exist, and arguing that the burden of proof thus lies on atheists to prove their claim.
This is correct, but it confuses and conflates two things. It assumes that the assertion "God does not exist" is the same thing as rejecting the assertion "God exists".
One might find it odd to be in logical limbo — how can someone reject both the claim that God exists and the claim that God does not exist? However, from a logician's point of view, this is a perfectly sensible situation to be in.
After all, there is no evidence to prove that God exists or does not exist. Thus, because there is no evidence for either hypothesis, both must be rejected.
When there is no solid evidence in favour of two diamterically opposed claims, then, how do we know what to believe? This is why there are so many agnostics and "soft" atheists out there — because they believe there might be a God, but don't believe in Him at the moment because they have not seen evidence of his existence.
One might bring up Pascal's wager — that it is better to believe in God than to disbelieve, because the former raises your chances of salvation if there is an afterlife. Believing in any God would increase the probability of a desirable outcome.
However, all this talk of logic and probability is utterly pointless when it comes to the question of God. The reason is simple — the concept of God exists outside the bounds of normal logic.
No matter how you phrase it, any hypothesis related to God cannot be disproven. The element of falsifiability is crucial for any hypothesis to be proved empiricallly.
Religion and God are matters of faith, not logic. Attempting to inject the idea of God into logical discourse does both faith and logic a huge disservice, because these are two realms which axiomatically cannot meet.