Saint Thomas Aquinas developed five arguments for the existence of God, which I have summarized:
- The Unmoved Mover – The ever changing universe must have something that moves it or that directs the change. God is that mover.
- The First Cause – Everything is caused by something and nothing can cause itself to exist. God is the first cause.
- The Argument from Contingency – Everything is perishable and considering all the variables working against the world, everything should be extinct. God is the imperishable being that allows perishable existence to continue.
- The Argument from Degree – We are able to see the world in degrees of goodness, truth, and nobility. There must be a standard by which to judge goodness and that standard is God.
- The Argument from Design – Unintelligent objects behave in regular and predictable patterns. Their behavior must be set or designed. God is the designer.