Marcion (Μαρκίων) of Sinope (modern Turkey)
If you look at my posts about Bayes’ Theorem and the existence of god (parts 2 and 3) you’ll notice that the probability of the Christian god goes down due to it being asserted that he has a role in evolution and the creation of the universe. If you don’t feel like slogging through those posts, here are the relevant arguments.
On life arising on Earth as opposed to other planets:
So if one were to say that P(Earth | H [i.e. Chrisian God]) is .99, then one is in effect saying that it would be very unlikely, or .01 probability, for the Christian god to create life on any other planet. What exactly is limiting the Christian god at this point? Why couldn’t the Christian god create life on Mercury if he wanted to? It seems to me that since all things are possible with the Christian god, we would have to distribute our probability evenly between the eight planets. We can’t have .99 for each planet because .99 * 8 is much greater than 1.00. Like I said in a previous post, probability is like energy. It has to be conserved. When everything is added up it has to equal 1.00.
P(Earth | H) in reality would be 1/8, or .125.
So I would estimate that P(Earth |~ H) would be closer to .9, with the planets on the outskirts of the [Goldilocks Zone] getting a decent chunk like .04, and the remaining five planets splitting up the .02. This is in fact what astrophysicists do when looking for planets outside of our Solar System. They concentrate on looking for planets that are within that star’s GZ and then concluding that those are the planets that have a high probability of water and thus a high probability of life (compared to other planets outside of the GZ). Methodological Naturalism for the win, I suppose!
So our formula to update our prior of .977 looks like this:
P(H | E) = P(E | H) * P(H) / [P(E | H) * P(H)] + [P(E | ~H) * P(~H)]
= P(Life on Earth | Christian God) * P(Christian God) / [P(Life on Earth | Christian God) * P(Christian God)] + [P(Life on Earth | NonChristian God, Atheism) * P(NonChristian God, Atheism)]
= .125 * .977 / [.125 * .977] + [.9 * .023]
= .1221 / [.1221] + [.0207]
= .1221 / .143
So our prior was bumped down from .977 to .8551. If there were no GZ planets (i.e. P(E | ~H) would be basically zero) and there was life on a planet anyway, then even if P(E | H) was .125, this would increase our prior probability from .977 to basically 1.00; we would have almost absolute certainty of the Christian god’s existence, according to the assertions of Christians.
So given evolution, and assuming equal distribution between theistic evolution and theistic non-evolution (I don’t have any a priori reason why the Christian god would pick evolution over non-evolution or vice versa), we would have the following Bayesian update to our prior probability of .8551:
P(Christian God | Evolution) = P(Evolution | Christian God) * P(Christian God) / [P(Evolution | Christian God) * P(Christian God)] + [P(Evolution | Atheism) * P(Atheism)]
= .5 * .8551 / [.5 * .8551] + [.99 * .1449]
= .4276 / .4276 + .1435
= .4276 / .571
Now, given no evolution, we would have the following Bayesian update to our prior probability of .8551:
P(Christian God | No Evolution) = P(No Evolution | Christian God) * P(Christian God) / [P(No Evolution | Christian God) * P(Christian God)] + [P(No Evolution | Atheism) * P(Atheism)]
= .5 * .8551 / [.5 * .8551] + [~0 * .1449]
= .4276 / .4276 + ~0
So if there were no evolution, then the evidence for the Christian god goes up from .8551 to approximately 1.00. I have to stress that in reality no evolution would simply be evidence against atheism. Surely the Greek gods or some other supernatural force could have created life on Earth if there indeed was no evidence for evolution, and that would have to be included in the H of ~1.00. This is the reason why P(No Evolution | Atheism) is only approximately zero and not zero. ~H was supposed to be both atheism and some other, non-all powerful god(s) besides the Christian god.
But as it stands, evolution is the most likely explanation for the emergence of human beings on Earth. And evolution does indeed favor atheistic evolution over Christian theistic evolution.
Now our prior probability for the existence of the Christian god is .7487 and the prior probability for the existence of a non-Christian god(s) or atheism is .2513.
On the creation of this universe as opposed to some other universe:
According to this apologetics website the probability of the current arrangement of our universe’s constants is the equivalent of picking one red dime out of a pile of 1037 dimes. Or, P(Current Universal Constants) = 0.0000000000000000000000000000000000001.
Back to our Total Probability formula:
0.0000000000000000000000000000000000001 = P(Current Universal Constants | Christian God) * .7412 + P(Current Universal Constants | Non Christian God, Atheism) * .2588.
0.0000000000000000000000000000000000001 = ???? * .7412 + P(Current Universal Constants | Naturalism, Atheism) * . 2588.
It looks like the equation has to be P(Current Universal Constants | Non Christian God, Atheism) > P(Current Universal Constants | Christian God) in such a manner that makes the Total Probability equal to 0.0000000000000000000000000000000000001. Since P(Current Universal Constants | Christian God) is basically zero — the majority of the probability capital goes into P(Other Universal Constants | Christian God) — this means that P(Current Universal Constants | Non Christian God, Atheism) is equal to a miniscule amount more than P(Current Universal Constants). At this point, it might as well be equal to P(Current Universal Constants).
Since P(Current Universal Constants | Christian God) is basically, zero, this means that the probability of the Christian god’s existence given the current universal constants is also basically zero. It’s not actually zero because zero isn’t a probability. I’d like to say that I’m the first one to make that argument, but it already looks like other people have come to a similar conclusion about the fine-tuning argument.
You can see that the probability of the Christian god’s existence takes a hit with all of these arguments; the reason it takes a hit is because the Christian god is unfalsifiable. But what happens if no one ever asserted that the Christian god was responsible for the creation of the universe or life on Earth?
That just so happens to be the description of the Marcionite god.
According to Marcion, his good god was an alien. Previously unknown to humanity before the descent of Jesus from heaven, this god had no hand in the creation of humanity or the universe. All of that was on the hands of the Jewish god. Marcion’s god just sort of “happened” onto humanity and felt sorry for us and decided to offer unconditional eternal life to those who believed in him.
There’s no reason why the same sort of logic couldn’t apply in the context of evolution; the Marcionite god just happened upon an already evolved humanity and the subsequent divine passion play would pan out. Since it is never asserted that the Marcionite god had a hand in creation or evolution, he doesn’t take any hits in probability in comparison to the (orthodox) Christian god.
In short, a non-creator god is compatible with evolution. One of the reasons I think Marcion’s theology is one of the most logical iterations of Christianity.