The ‘Kalam’ cosmological argument of the philosopher William Lane Craig (although it actually dates back to the medieval times) proves the existence of god by having a premise and using it in the following premise. It is as a matter of fact a series of connected arguments. If you will study closely the meaning of the ‘Kalam’ cosmological argument, it conveys that it is not possible for the universe to have an infinite past. One thing should be caused by another thing. It shows that the series of causes cannot go back to infinity, that is, some being must exist necessarily as a start of everything.
Accordingly, the universe should have a beginning otherwise, it has no beginning at all. If the universe doesn’t have a beginning, there should be an infinite number of years that has already elapsed in history. And since no infinite number of years can be completed as such, the universe should have a beginning. Either there is a cause of the beginning of the universe or it is uncaused. If one will say that the beginning of the universe is uncaused, it will mean that the universe existed from nothing which is impossible, so the universe definitely has a cause. This cause should be a part of the universe or an external force. The cause of beginning of the universe cannot be inside/within the universe so the cause of the universe has something to be external and supernatural. The universe depends on the existence of something supernatural – God.
Similar to the ‘Kalam’ cosmological argument, Thomas Aquinas’ 5 ways also points out that the infinite series of causes is not impossible and that the existence of a necessary being is a must. But the reasoning behind the ‘Kalam’ cosmological argument is different from how Thomas Aquinas’ proves God’s existence. ‘Kalam’s reasoning is mathematical; Aquinas’ on the other side used theology and philosophy combined. He used facts of change, variation and purpose to prove the existence of God while ‘Kalam’ uses premise for the following premise. There is the same intent, but the processes are different of because of the difference in culture between the philosophers who pushed through with the arguments. The ‘Kalam’ cosmological argument has Islamic roots while Thomas Aquinas’ 5 ways is evidently influenced by Christianity.