Question for Atheists

[Mister Agenda]

Hi! I've been trying for a while now I get an atheist's response to a particular line of thinking, but have thus far been unable to help anyone understand it or give a coherent thought about it. I'm hoping here is a better place to find some discussion on the matter!

Welcome to the forum.

If the universe is entirely material (which it must be under atheistic thinking), then everything that exists or happens is fundamentally just chemicals reacting.

Don't you think it would be courteous to ask us what we think instead of telling us what we MUST think? Atheism doesn't exclude dualism or idealism, it only excludes believing in any deities. Atheism and materialism are not synonyms. I've met atheists who believe in ghosts and astrology. The only thing all atheists have in common is a single opinion on a single topic. We're just like theists in that respect, and I'm sure you know how diverse theists are.

Chemicals, however, cannot act reasonably or morally. We can't take one test tube and say that the mixture in it is "more right" than the one in another tube. Natural laws simply dictate their behavior.

Yep.

Humans and their thoughts and beliefs, as parts of the universe, are merely chemicals as well.

Here's where you start going off the rails, with the word 'merely', as though a whole can't be more than the sum of its parts. That's a fallacy of composition (we're made of chemicals, therefore all we are is chemicals).

Every idea is a natural string of reactions in the brain. The reactions in one mind lead someone to be an atheist while the reactions in another mind lead to a theist. Sort of like different outcomes in two test tubes.

Not really very like that at all, as now you're talking about moral agents, not chemical compounds.

On what basis then can we say that one thought or belief is more rational than another?

It really concerns me when people have difficulty distinguishing between rational and irrational without appealing to a deity. I'm left with trying to determine if they're being disengenuous or merely blinded by faith.

Dead chemistry can't be spoken of in terms of reason.

By definition, we are 'live chemistry'.

We are all parts and products of a giant chemical universe, atheists and theists alike. How can the universe be behaving unreasonably in one place but not in another? It just is.

Composition fallacy seems a particular weakness of yours. The parts of something are not constrained to behave like the whole. If a wall is fragile, that doesn't mean the bricks it's made of are.

Lines of reasoning become totally subjective since we are all slaves to our particular chemistry.

That is a claim. You can make a case that use of reasoning is at least partially subjective, but you haven't made a case that it is totally subjective and I am entitled to reject the claim that it is until you do.

But if reason is subjective, we lose any grounds we had of evaluating statements.

When you build your castle on a foundation of fallacies and unsupported assertions, you can't expect it to be very sturdy.

If my chemistry makes me think you are unreasonable and yours does the opposite in your brain, since no reaction can be said to be rationally superior to another, then there can be no meaningful debate. Ideas are all equally natural. Isn't that kind of a problem?

Not really, since you've failed to establish that it's the case.