From PZ's Place: Adam, USA, on Why I Am An Atheist:

I was raised in a creationist, fundamentalist home. If you’ve ever seen those videos where Ken Ham tells the crowd of kids to ask scientists, “Were you there?”, then you’ve seen a little bit of my childhood. I looked forward to getting our quarterly copy of “Answers in Genesis” (a magazine that Ham’s organization puts out). Later my dad subscribed to their “Technical Journal” of creationism because I was so interested in nature and science. When I was very young I was at one of those presentations that Ken Ham gives, and I am embarrassed to admit that at one point I even did ask a geologist “Were you there” as he talked about rock formations in Mammoth Cave.

I went to church at least twice a week, was in a christian school until college, listened to christian music exclusively, was in a very christian Boy Scouts of America troop, and I didn’t know a single person who wasn’t from one of those circles. All of my knowledge of ‘Atheists’ and ‘Darwinists’ came from creationist writings. I never had a ‘rebellious’ phase and was eager to please the authority figures in my life. So I really didn’t have any motivation for questioning the dogma I’d been given. I was growing up to be a zealous defender of “scientific creationism”.

And that was what brought it all crashing down for me, starting around my 16th birthday. I wanted to engage the other side and fight the good fight for Jesus, so I decided to figure out what the “evolutionists” could possibly have to say for themselves in the face of our awesome arguments and “facts”. The first thing I looked into was the claim that fossils formed over millions of years. Every real creationist has seen pictures of ‘petrified’ hats, boots, clocks, etc. This seemed like pretty good evidence that the scientists were wrong. But with a little bit of reading I found out that the hardened artifacts that the creationists were showing off were not, in fact, fossils. They were simply encrusted with calcium deposits. I also learned that replacement fossilization (where the organic molecules are replaced by inorganic minerals) occurs slowly because of diffusion rates, which are very easy to determine experimentally.

I was concerned that my heroes had been misinformed on that issue, but my faith was far from shaken. I simply thought that we would need to look deeper and we would find a way for fossilization to occur rapidly (in those days I planned on becoming a ‘creation scientist’). And I was excited about writing an explanatory article for Answers in Genesis because I really thought at the time that they would want to correct their error.

But while I was doing that I also started looking into ‘carbon dating’, which was another topic that was often ridiculed in creationist literature. I was told that it all depended on the assumption that everything had always been basically the same on the earth, but since god had magically created the earth in some unknown state and then flooded the whole thing that those assumptions were flawed. I was curious as to just what those ‘assumptions’ were and did some reading. I very quickly learned that carbon dating is only one of a large number of radiometric dating techniques, all of which agree on dates. And the ‘assumptions’ of other dating techniques (especially potassium-argon dating) were really impossible to argue with and produced data that was definitely incompatible with a young earth.

I then looked into a whole range of topics covering geology, cosmology, and biology; and literally everywhere I looked I saw dishonesty coming from the creationist side. So I briefly looked into ‘Old Earth’ creationism and ‘Theistic Evolution’ but ironically I had already been inoculated against those ideas by my Young Earth Creationist upbringing. The theology made far less sense and was even less consistent if you accepted an old earth. And by that point I was so disillusioned that I was critically thinking about Christianity itself and realizing just how ridiculous the beliefs were. I still considered myself a believer but was having serious doubts.

When I finally started thinking of myself as an atheist it wasn’t because of evolution or theology (this was only a few years after starting down the path of reason, but they were long and painful years). My parents got sucked into alternative medicine and I tried extremely hard to show them that they were being fooled by opportunistic charlatans. But I made no progress and was baffled at how people could believe something that had no positive evidence and was so obviously silly. And that’s when I became an atheist. I saw the clear parallel between religious belief and fake medicine, and I gave up my belief in god entirely. I’ve been religion-free for six years and my life has only gotten better. I am openly an atheist with everyone (except my parents, who might actually be killed by that news) and I really do think the future is bright for rationality and secularism.
Adam
United States

Adam makes two main points:

1. Young Earth Creationism doesn’t stand up to scrutiny.

2. The “clear parallel between religious belief and fake medicine” is an example of people believing something without “positive evidence”.

I agree with Adam’s conclusion regarding YEC. YEC is a blatant attempt to prove the literalist “truth” of the biblical story by retrofitting certain concepts into the premises, which is rationalization.

The second point, however, is pure Philosophical Materialism, comparing the material evidence requirements which are lacking for fake medicines to the rational argument for non-physical existence which also lacks material evidence because it is non-material: a legitimate lack. Or at least something similar to that, perhaps this:

IF [ fake medicine fools people ], THEN [ God does not exist ].
Fake medicine does fool people,
THEREFORE, God does not exist.

Rather than assign the obvious logical fallacy to this, let’s take the inverse as a test:

IF [ fake medicine does not fool people ], THEN [ God exists ].

The existence of God does not hinge on whether fake medicine fools people. And it does not hinge on whether material evidence exists:

IF [ there is no material evidence for a non-material first cause ], THEN [God does not exist ].

However, there is evidence of both physical and historical provenance available; this evidence has not been refuted; so the premise is false. So the inverse statement would be this:

IF [ there is material evidence for a non-material first cause ], THEN [God exists ].

This is also a non-sequitur, and renders the proposition false – on top of the premise of the proposition being false as well. Miracles cannot be disproved materially, yet they do not prove the existence of God conclusively; they are merely additional data points in the probabilistic proposition concerning a non-physical existence, one which is an agent.

Summary: Adam was disillusioned by YEC starting around his 16th birthday, and then was susceptible to Philosophical Materialism, which he adopted a “few…long and painful years later”.