Here is the Kalam Cosmological Argument (KCA):

1: Whatever begins to exist had a cause
2: The universe began to exist
3: Therefore, the universe had a cause

This post is the conclusion of a three-part series responding to a Christian defense of the KCA. Part 1 here.
Below, the skeptical argument is shown in bold and the Christian response in italics.
“8. There are non-theistic explanations that remain live possibilities.” Even if the universe has a beginning, there are possibilities besides God. If you’re thinking of aliens or the multiverse, that just pushes the problem back a step.
What is it with this obsession for an immediate answer? Can’t we just say, “I don’t know”? That approach has done well for science, because it puts the spotlight on interesting questions, which then tend to get answered.
Of course, it’s clear why apologists demand an answer right now. They know that science regularly replaces supernatural explanation with evidence-based explanations. Their time window is brief, and they want to score some points for “God did it!” before they have to move on to another unanswered scientific question and hope that everyone forgets the last one they embraced.
Some have argued that a computer simulation like the Matrix will eventually be no more difficult than a homework assignment. Given that, is it likelier that we’re in a simulation or reality? (I don’t know what I think of this option, but I wanted to throw it out there as yet another non-God alternative.)
The multiverse would indeed demand an explanation, but why imagine that God is it? God has never been the answer to anything. If God is the explanation, show that he exists first and then infer that he created the universe/multiverse. The Christian god who loves us and desires a relationship would be obvious, and the obtuse KCA wouldn’t be a way to find him. Every clue points to naturalism as the explanation for this and other unknown puzzles.
“9. Popular-level science teaches the universe had a beginning, but someone says the real science shows it doesn’t. We aren’t given any argument as to why it’s really the case that a potentially-successful model for the beginning of the universe shows no finite beginning. We’re simply to take someone’s word for it, when we actually have physicists and scientists admitting these theories don’t work.”
There’s not much to respond to here, but I include it for completeness. I’ll just note that cosmologist Sean Carroll’s list of proposed models for the universe (there are many) includes a beginning-less universe (more).
“10. The KCA relies entirely on current science, and science can change.” “First, simply because some claim remains open to change does not mean that claim cannot be accepted as true…. Of course we can claim it is true!”
As long as we remember that science can change (and overturn a previously held conclusion), I’m fine with science being used in an argument to support the KCA.
“Second, the KCA does not rely entirely on science. In fact, the second premise (“the universe began to exist”) can be defended solely on rational argumentation.”
I think we’ve found your problem: thinking that “rational argumentation” (can I call this “common sense”?) is reliable at the frontiers of physics (see claim #3 above). The origin of the universe is within the domain of quantum mechanics, remember? You check your common sense at the door.
QM has already defeated the first premise, “whatever begins to exist had a cause” (see claim #1 above).
11. Your first cause falls to the infinite regress problem. If God is your first cause, what created God? God didn’t begin to exist. The First Cause must logically precede all else. There simply can’t be, by definition, anything that came before.
Be cautious when a definition brings something into existence. Like the Ontological Argument, which just thinks God into existence, that may be too good to be true.
You didn’t say this, but let me just add the caution that apologists shouldn’t respond to a scientific question with a theological claim. “My religion says that God was uncreated” is no answer in the real world.
You say that God didn’t have a cause … just because? That’s magic, and I need evidence. Why does God not need a cause if everything else does? Why is God eternal, but nothing else is? How did God create something out of nothing? How can he create the universe when he was outside of time—doesn’t deciding and acting require time?
The most charitable view is that you’ve resolved “What caused the universe?” with God, but you now have these new questions about God. You’ve simply repackaged the question, not answered it.
And if God can exist eternally, maybe that’s true for the universe (or the multiverse).
Conclusion
The author concludes:

Each objection has been dealt with by providing an answer. This means that each Christian, and each person, is rationally justified in accepting the KCA. If that is true, then it seems that the KCA’s truth implies God–not just any God, but the God of the Bible!

Nope. My original post is intact. I leveled five attacks on the first premise and three on the second. None of those were addressed in this article. No, rational people are not justified in accepting the Kalam Kosmological Argument.
You’ve probably seen the famous Sidney Harris cartoon where one scientist points to an involved equation on the blackboard and says to his colleague, “I think you should be more explicit here in step two,” where step two says, “Then a miracle occurs.” God is the step two—the implausible savior of Christians’ apologetic arguments.

The universe that we observe
has precisely the properties we should expect
if there is, at bottom,
no design, no purpose,
no evil, and no good,
nothing but blind, pitiless indifference.
— Richard Dawkins

I feel like I’m diagonally parked
in a parallel universe.
— seen on the internet

Image credit: NASA