William Lane Craig is perhaps the most popular Christian apologist out there. In almost every debate I have seen of his, he begins with the same 5 arguments for the existence of God. I thought I would give a series of 5 articles addressing each one of these arguments in turn, starting with the Kalam Cosmological argument.
The argument goes something like this:
1. Everything that has a beginning of its existence has a cause of its existence.
2. The universe has a beginning of its existence.
3. The universe has a cause of its existence.
4. If the universe has a cause of its existence then that cause is God.
5. God exists. 
There are a number of problems with the first premise alone. Nothing truly has ‘a beginning of it’s existence’ it is simply a recycling of matter in a different form, yes there are certain things that cause matter to take on a different form such as chemical reactions or nuclear fusion etc, but the only real ‘beginning of existence’ was the beginning universe itself – which created all the matter that recycles itself into different forms according to different causes. We do not currently know what, if anything caused the big bang to happen. So if nothing that we can observe actually begins to exist, it is merely the recycling of existing materials, the only beginning of existence is the beginning of the universe itself – which we simply do not know the cause of, or even if the beginning of the universe required a cause in the same way that existing matter requires a cause in order for it to take on a different form.
In fact the only thing that we can observe that begins to exist, rather than being a recycling of existing matter is virtual particles, and these appear spontaneously without cause  – this is in direct contradiction to the assertion of the first premise. In short, there is absolutely no reason to grant the first premise of this argument; matter can be caused to take on different forms – but this is very different from beginning to exist, and our observations of things that do begin to exist contradict the assertion that they require a cause.
The second premise is also problematic. The universe as we know it began with the big bang, but this is not to say that it did not begin from some prior state of existence. However, even if it did begin to exist, I have shown that the first premise is faulty; things that begin to exist do not necessarily require a cause, so even if we grant the second premise the conclusion does not follow from the second premise alone.
The forth premise, that the universe had to have been caused by God is a completely unfounded assertion. If we assume that the universe had a cause for it’s existence, it does not necessarily have to be God. M-Theory provides a cause for the big bang that is not God, rather a collision between membranes  – although M-theory is currently not supported by any evidence (it predicts some known facts about the universe though), it is an example of a theoretically sound explanation for the cause of the big bang that is not necessarily God, demonstrating that the fourth premise is merely an assertion that is unsupported and does not follow even if we grant all the premises in the argument so far.
This argument simply does not prove God’s existence no matter how confidently Craig asserts that it does. The Kalam cosmological argument is not a good argument.