I think there's an important burden-of-proof issue here.
I'm not claiming “nature is all there is,” so I don't have to prove that claim in order to reject your argument. My position can simply be: your argument has not established that a cause beyond nature exists, and therefore I don't have sufficient reason to believe that God exists.
And your argument isn't merely “following the evidence.” You're relying on two substantive philosophical premises:
P1. Everything that begins to exist has a cause.
P2. The universe began to exist.
C. Therefore, the universe has a cause.
The logical form is valid. The question is whether the premises are justified.
And the Stanford Encyclopedia of Philosophy's current treatment of the cosmological argument explicitly treats the causal principle and the universe's beginning as disputed premises. It describes the Kalam as a specific version of the broader cosmological-argument family, not as an established scientific fact that automatically proves God.
First: P1 isn't something you've demonstrated
You say:
«“Whatever begins to exist has a cause.”»
But what exactly is the evidence for this universal metaphysical principle?
Our ordinary experience shows things beginning to exist within an already-existing physical reality. We don't have ordinary experience of an entire spacetime universe beginning to exist.
So there's a difference between:
“Everything we've observed coming into existence has a cause.”
and
“It is metaphysically impossible for the totality of physical reality to begin without a cause.”
The second statement is much stronger.
Even defenders of the Kalam recognize that its causal principle requires philosophical defense. The SEP discussion notes that William Lane Craig ultimately grounds the principle in the metaphysical intuition that something cannot come from nothing, while critics such as Richard Morriston and Graham Oppy challenge whether this principle is an a priori truth.
So you can't simply say “it's what we observe.”
We're discussing the origin of the entire physical system in which our observations occur.
That's precisely where the argument needs justification.
Second: P2 doesn't follow simply from “the Big Bang happened”
This is where I think your wording is doing too much work.
“The universe began to exist” can mean several different things.
It could mean:
A. Our observable universe has a finite past.
B. Our current spacetime description has a past boundary.
Or it could mean:
C. Absolutely all physical reality came into existence from literally nothing.
Those aren't automatically equivalent.
The Big Bang model tells us about the early state and expansion of our universe. It does not, by itself, establish the metaphysical proposition that there was once absolutely nothing whatsoever.
And notice what I am NOT saying.
I'm not saying:
«“Science has proved the universe is eternal.”»
I'm saying:
«“You haven't established that the Big Bang equals an absolute beginning of all reality.”»
That's a much more modest claim.
The philosophical literature treats the question of whether the universe has an absolute beginning as a genuine point of debate. The SEP specifically discusses competing arguments concerning temporal beginnings, infinite regresses, cosmological models, and what “beginning” means in these arguments.
Third: let's grant both premises anyway
Here's where your argument still doesn't reach God.
Suppose I grant:
P1. Everything that begins has a cause.
P2. The universe absolutely began.
Then:
C. The universe has a cause.
Fine.
But that's not yet:
C. God exists.
You've established a cause.
You haven't established that the cause is:
- conscious,
- personal,
- intelligent,
- omniscient,
- omnipotent,
- morally perfect,
- or Christian.
That's not a minor detail.
It's the central identification problem.
In fact, the standard Kalam formulation itself adds another step after the universe's cause. The SEP presents Craig's version as going beyond the three-premise syllogism to argue that the cause must be personal. That additional move is itself philosophically controversial.
So if you want to argue:
Universe → cause → personal agent → God
you need to defend each arrow.
You can't simply put “God” at the end of the syllogism because that's the conclusion you want.
Fourth: “beyond space, time and matter” isn't the same as “God”
Even if the universe has a cause that isn't part of our spacetime, all you've established is something like:
«There is an explanation outside our physical universe.»
That's interesting.
But it doesn't tell us what that explanation is.
You still need an argument for why that cause must be a mind.
You need an argument for why it has intentions.
You need an argument for why it is omnipotent.
You need an argument for why it is omniscient.
And then you need another argument for why it is the God of Christianity.
Those are additional philosophical arguments, not consequences that a