The Kalam Cosmological Argument is one of the traditional, philosophical, arguments for the existence of God. The idea is that everything must have a beginning; therefore the universe must have a beginning, therefore God. (Which those who use this argument naturally assume is the God of traditional western religion.)
This is the kind of argument, like so many similar arguments, that is persuasive only to those already inclined to accept its conclusion. There are of course several problems with this argument. (If it were really a tight philosophical argument, why would the world’s intellects not be convinced and this debate not be foreclosed?) Wikipedia has this post about the argument, with simple refutations and descriptions of more technical responses. For a detailed technical response by an actual physicist, see Sean Carroll: Does the Universe Need God?. And Carroll, who debated the Christian apologist William Lane Craig a couple months ago, specifically addressed this argument, as summarized in his post-debate reflections.
My own take is twofold.
First, the premise is assumed without empirical evidence. How does anyone know that everything that exists needs a cause? And, did the universe actually begin to exist at some point? Perhaps the universe is an exception; perhaps this assumption about cause is merely a psychological assumption by the minds of human beings. (There are in fact cosmological theories that take our universe as one of many, born out of previous universes via black holes, in an endless series. See Lee Smolin, and Stephen Hawking. Or, cf. Hawking, that space-time is a kind of infinite loop; the ‘big bang’ is an apparent beginning only in the way that a circle, or a globe, has a beginning.) Does a circle have a cause? If a circle does not have a beginning, does it therefore not exist by this premise?
There’s a YouTube video about this, which suggests that believing that something can exist without a cause is akin to magic. Well, if the answer to the universe existing is, um er, ‘God’, then why can God exist without a cause? The usual answer is that ‘God’ is outside human understanding or need for a cause, but this is begging the question. Why shouldn’t the universe itself have this state?
Later in the video: it uses one of the oldest, silliest, most easily discredited arguments about evolution and cosmology: that somehow the “second law of thermodynamics” discredits these ideas. Hello? The second law of thermodynamics is as much a scientific conclusion as is evolution, or cosmology. Get it? You can’t use science when it’s convenient for your side, and dismiss it when it’s not. (That is, maybe the second law of thermodynamics is false. That’s as plausible as evolution or cosmology being false.)
Third, the video claims that anything must have a beginning.
Second– Even if the video’s argument were valid, so what?
The video jumps from the dubious conclusion about the need for something to have caused the universe to the assumption that this cause must be the traditional idea of ‘God’ – as if the only option for this cause has to be the ‘God’ the arguer happens to believe in. Of course, anyone subscribing to any of the other thousands of religions around the world could use this chain of argument to justify their *own* beliefs.
Really, people of intelligence have been debating these issues for centuries, even millennia. If there were really an argument, or arguments, to ‘prove’ the existence of ‘god’, why would we still be debating this? Mathematics and science has generated arguments based on reasonable premises for millennia (see Cosmos), and the result is our high-technological civilization, where you can post invalidated arguments about the existence of ‘god’ on an internet that depends on a worldwide network of computers and satellites that is a result of centuries of advances in physics and cosmology. While religious apologists fall back on philosophical arguments from centuries past that have been discredited, again and again, by modern intellects. Because they always have an audience of relatively uneducated, credulous people, to support their positions. Is the intellectual capacity of human beings to be dismissed? To some, maybe. Perhaps happiness, in ignorance or delusion, is all that matters.