I'm sure the precise reasons for their faith vary from Christian to Christian, but by and large, I imagine they are like most other people and believe what they were told as children, and then enlist ex post facto arguments to justify that belief. I'm not saying that's what you are doing, since certainly there are exceptions. That said, do you find it a curious coincidence that the exact faith you were raised in just happens to be the correct one? Quite a stroke of good fortune for you, no?
"So let's imagine we are in one of the logically possible omniverses where the first cause does not exist. But this causes a logical contradiction, for now we are saying that this first cause, which exists by its very nature, does not exist."
The thing about scientific knowledge is that you don't know what you are missing from your current vantage point. I'm sure there were once people who couldn't imagine any advance in knowledge that could explain an eclipse, so it must be God. Almost everything we know about cosmology, we've learned in the last hundred years. And as I have mentioned a couple of times now, cosmologists currently have models and equations that suggest laws which exist outside of space and time that can create an inflationary universe from nothing. I'd say that's already pretty close to rendering God unnecessary. Who knows where we will be in 100 more years?
So then, to clarify, you would lower your confidence in God's existence if the first cause argument was found wanting? By roughly how much?
The difference between empirical necessity and logical necessity is this:
Empirical: You can imagine an alternate universe where I did not father children, even though you know I did father them in this universe.
Logical: You cannot imagine an alternate universe where 2+2=5.
So yes, the existence of a first cause is logically necessary. And the attribute of existing by its very nature (i.e. being uncaused) is embedded in the concept of a first cause. But beyond those basics, there is a lot of room for variation in a first cause. I don't see at all where you have demonstrated otherwise. You said:
This is not a logical contradiction because the omniverse is, by nature, a closed system. So First Cause X exists by its very nature within the closed system of Omniverse A. But First Cause Y exists by its very nature within the closed system of Omniverse B. A first cause of some kind is logically necessary in all possible omniverses, but it doesn't follow that the same first cause must exist in all possible omniverses.
I was surprised to learn that the laws of physics don't actually exist. You said, "laws are not an actual thing that exists, but rather descriptions of how actual things that exist operate." By this logic, moral laws must not actually exist either, and perhaps our conversation is over?
I don't think your description of "a free-willed being" as the cause of a decision holds up under scrutiny. Imagine the following exchange:
Officer: What caused you to kill your wife?
Suspect: I'm a free-willed being.
This appears to be a fancy way of saying "I chose to do it." But no one is disputing that humans make choices. The question is why one choice was made (i.e. murder) rather than another.
In the case of our hypothetical murderer (here we are, back to hypothetical murderers!), there may be a number of proximate causes (he found out she cheated on him, he was drunk, he just lost his job, etc) and more distant causes (he bought a pistol years ago and kept it loaded in his bedside drawer, he's been cheated on before, etc) And, of course, for any individual cause, we can ask the same question: Why was he drunk? Why did he lose his job? And each of these answers spawns another set of why's and so on. You must think something like this is true, right? I mean, we aren't all wandering around making decisions about whether to murder people or not in a vacuum, are we?
"Meaning" is inherently subjective in my view, so I don't find it troubling at all to "find my own meaning." But even if I did find it depressing that I am an insignificant speck of dust in a vast, uncaring universe, my feelings would have no bearing on the truth or falsehood of the matter.
Your robot-bug analogy is just Paley's watchmaker argument redux, and Darwinian natural selection already dispensed with that argument, so I have nothing further to add.
