A former agnostic, with doubts?

[Alex K]

"- The universe requires a cause."

No, it doesn't. Case closed.

And how would you argue that? I'm unsure how you can justify that opinion. xD

Then let me sureify you, at least to the extent that I think a justification is even necessary.

So in your opinion cause effect doesn't extend to the big bang? And it's just a wild unique temporary organization of our universe?

First of all, I'd like to shift the burden of proof to you.

But more concretely: the issue of cause and effect is not as clear cut as you might think. The arrow of time in physics (and hence the distinction between cause and effect) only arises as a statistical effect in physical systems with many degrees of freedom/particles. It is linked to the increase of entropy (with the universe going from less likely to more likely configurations).

Simple physical systems, like e.g. a few point masses attracting each other like a simplified solar system, are completely time reversal invariant. Let them run backwards, and they obey the same laws and are impossible to distinguish (*). Only when many particles are involved, a backwards running movie would suddenly be recognizable because very unlikely things happen.

On top of this, the fundamental laws of physics are not even obviously deterministic because of quantum uncertainty. So cause and effect are not really fundamental properties of the universe, they arise because of the boundary condition of low entropy in the (by definition) "past".

It is so much less obvious that the concept should apply to the universe as a whole. You really need to carefully define what the word even means in this context before you can make this claim. Otherwise, the statement is meaningless and does not require refutation.

(*) there is a small violation of time reversal in the weak interactions. It is not obviously connected to the arrow of time.