The rancor between theists and atheists might be reduced if, rather than emphasizing their differences, commonalities were stressed. Usually, however, differences are emphasized.
Such differences are already apparent in the usual definitions. Thus,
• A theist is a person who believes in the existence of some god, with the word ‘theist’ derived from the Greek word theos meaning ‘god’,Meanwhile, an obvious commonality among theists, agnostics, and atheists is apparent by focusing on the concept of ‘belief’.
• An atheist is one who has concluded that there is insufficient evidence to justify a belief in god, with the word ‘atheist’ derived by negating the word ‘theist’ with the Greek prefix a- , and
• An agnostic is one who maintains that he doesn’t know (e.g., about the existence of any god), with the word ‘agnostic’ (viz., ‘unknown’) derived by negating (again with the Greek prefix a- ) the Greek word for ‘known’ (gnōstos).
One way to express belief – in fact, the way to express belief precisely – is to express it as a probability. For example, you might say that you ‘believe’ that the Sun will rise tomorrow, or you might say something similar to: “My estimate is that there’s a 99.999999% chance that the Sun will rise tomorrow” (or whatever numerical value you might assign to the probability that the Sun will rise tomorrow). Similarly, a theist might say, “I think that there’s a 99.999999% chance that God exists”, whereas an atheist might respond, “Well, I think that there’s only a 0.000001% chance that God exists.”
A commonality among theists and atheists is then apparent: by whatever means they’ve used, both have reached some opinion about the probability of some god’s existence. Such opinions are held more-or-less strongly, depending on each person’s experiences.
Among different individuals, there’s normally quite a large variation in such probability estimates. For example, a particular theist might hold that there’s a 90% chance that some god exists – while simultaneously leaving a 10% chance that the god doesn’t exist (since the sum of the probabilities for two mutually exclusive possibility must sum to unity or 100%). Similarly, a particular atheist might maintain that there’s only a 10% chance that some god exists – while, for the same reason, simultaneously leaving a 90% chance that the god doesn’t exist.
In general, an atheist is one who has concluded that the probability that some god exists is in the range from just over 0% to just under 50%, while a theist is one who has concluded that the probability that the god exists is in the range from just over 50% to just under 100%.
The specific value of 50% (for the chance that some god exists) is claimed by the agnostic. That is, an agnostic claims no knowledge of whether some god exists or doesn’t exist, and therefore, just as when one doesn’t know whether the toss of a fair coin will yield ‘heads’ or ‘tails’, specifying a probability of 50% (or odds of 50-50) is equivalent to saying: “I don’t know.”
Meanwhile, the values of exactly 0% and exactly 100% must be excluded because of the nature of reality. That is, no realistic atheist will say that there’s exactly zero chance of any god existing and no realistic theist will say that there’s exactly a 100% chance of any god existing, because, in reality, we can’t be certain of anything: for all we know, none of us may exist; we all may be just simulations in some humongous computer game!
Stated differently, certainty is available only in closed systems (e.g., games), whereas in reality, we all must live with uncertainty. For example, in the game of poker, you can be certain that a flush beats a straight, but in life, you’ll never know all the cards that you’ll be dealt.
I then wonder if the rancor between theists and atheists could be reduced if all would see that their differences are just a matter of degree. Again, atheists have concluded that the probability that some god exists is in the range from just over 0% to just under 50%, agnostics choose the value of 50%, and theists have concluded that the probability is somewhere between just more than 50% to just under 100%. Consequently, fundamentally, the differences are derived from different estimates for a particular probability.
Maybe the rancor would be reduced if, rather than people proclaiming and promoting their estimates for the probability of any god’s existence, we’d all focus on explaining to those who are interested how we reached our individual estimates. Maybe, if we all work at it, we would conclude that all such estimates are approximate and should be flexible. As a minimum, surely we can all agree that those who advocate or engage in the killing of people whose estimates for such probabilities differ from theirs thereby commit a crime against humanity and should be constrained.