First, the universe is unreasoning. Agreed?
I can't see any reason to disagree with this.
We are reasoning beings, so somehow reason is derived from the unreasoning (from something that is not reasoning). Is that reasonable to believe?
I think "has resulted from" is more accurate than "is derived from."
Third, the universe is unreasoning, yet through our reason, we find meaning IN the universe, in what exists. Why should we expect to find reasons in a universe that is devoid of reason, just events of happenstance?
We don't find it there. We PUT it there. We assign it. This is where we differ. And I think you're mixing meanings again. Can you give me a reason, for example, for all these exoplanets we keep finding? Can you give me a reason in the Bootes Void? I can give you reasons FOR both, but reason IN neither.
Fourth, if there is no reason for the universe there is no way of explaining why it is here. There is no "why." As you say, it just is and just came to be. Is that logical to believe?
Yup, because there's nothing so far that points us in any direction otherwise. And it doesn't matter any further than because it's here, we're here.
If it came to be then what is the cause? Logically, it can't self-create, can it? Surely, for something to create itself it would first have to be, or else you have something coming from nothing. Something from nothing is not something you witness, is it? It is a logical impossibility, is it not? How can you derive something from nothing?
Don't go down the "everything that exists has a cause" CALAM stuff, because you know that just leads to well what created whatever you think created the universe? I don't know what caused it. I don't know if something can come from nothing, but we certainly haven't witnessed that process. I don't know how it happened, but neither do you. I'm just stopping at I don't know. You're taking an unearned step (two, at least): well I don't know, so it must be someone! This is an argument from ignorance.
Why did the Big Bang happen (if that is your mode of the start of the universe), or what caused it?
Don't know and makes no difference. It happened.
How did we get this "singularity?"
Where did it come from?
Don't know, not sure that it matters. But I'm sure you're not going to say Jesus put it there, otherwise why leave it out of the bible?
Why do we have gravity and gravitational pull?
Why does the earth revolve around the sun at the precise distance?
These are easily answered scientific questions. Appealing to the supernatural to explain them is your job, not the job of someone who just says "The math works out that way."
The Christian explanation, and it is a reasonable one, is that we discover these laws because there is a Lawgiver that has crafted the universe. Mathematics is a conceptual science. We are able to explain how things in the universe work because there is a Mind behind the universe, not just random chance happenstance.
This last bit proves you don't care about any of the other bits at all, gravity, the big bang, etc. No matter what the scientific explanation is, you just move god one step further back: well, gravity exists because of matter's density in relation to spacetime, and gravity behaves in such and such a way that comports with these models, but that is just how God set it up! And he WANTED us to discover it eventually! It's special pleading (uncaused cause) + god of the gaps. I'll give you that it IS difficult to penetrate using reason and logic, but the flaws in it are glaring. If the universe began to exist, then it had a cause. That cause = God. What caused God to exist? Oh, he always existed! Well then why can't the universe in one form or another have always existed? You're starting with an end answer and trying to make the problem fit, rather than look at the problem and find the answer. In rough mathematical terms, you have an equation with a string of like 14,000 variables all undefined, but the equals sign is followed by the number 9852349572112359. You're insisting you know each variable because you presuppose the answer, the problem is that with ONLY variables on one side of the equation, you cannot have a numerical answer, and the more you add to the equation, the more difficult it gets to arrive at an answer. Example:
X + Y =35. How can you solve for X or Y without one of them ending up on the wrong side of the equals sign? How many different answers are there? How do you know if X is 30 and Y is 5, or X is 16 and Y is 19? You can't. You're insisting you do. Now, what if that equation because X + Y + Z = 100? See the problem? These cannot be solved in a way that does not ALSO move a variable to the wrong side of the equals.
You suppose (as presuppositionalists do) that not only is there a lawgiver, but that it's YOUR VERSION of that lawgiver. I would point you to another topic if you want to answer this: in the history of mankind, let's call it 200,000 years, folks like you are always quick to point out there have been FAR more people who believe in "something did this" than there are people like me, who say there's no reason to believe that's the case and ask why you do. Somehow, you think this supports the truth of there being something else out there. One of the many problems with this argument is plain: there have also been FAR MORE, FAR FAR MORE, people that never ever ever believed anything remotely close to what you CURRENTLY believe. Yet you are certain you're right and you use the belief in ANYTHING as support for believing in your specific thing.