1. The cosmological argument attempts to prove God's existence by arguing that the universe must have been created by a divine being since it is contingent and could not exist without a first cause.
2. Thomas Aquinas proposed five ways to demonstrate God's existence through an unmoved mover, an uncaused cause, possibility and necessity, degrees of quality, and design.
3. David Hume and Bertrand Russell objected that we cannot infer a cause for the universe since we have not observed its creation and it may be eternal and self-existent.