Cosmological argument

The cosmological argument is an attempt to prove the existence of God by the fact that things exist. It assumes that things must have a cause, and that the chain of causes can only end by a supernatural event. Other names for the argument are argument from universal causation, argument from first cause, causal argument and argument from existence. 
The universe exists, so there must be something that caused the universe. The first cause is claimed to be God. Thomas Aquinas said that God is the only thing that was not caused by something else, and that God created the cause of existence. The idea has been popular with many theologians and philosophers.