Can we know that God exists through human reason alone?
Yes. The Catholic Church teaches that human reason is capable of arriving at the certain knowledge of God as the origin and end of all things, simply by reflecting on the created world around us.
When we look at the order, beauty and intelligibility of the universe, our minds can perceive that something so vast and intricate cannot be the product of blind chance. In this way, philosophy and human reflection can recognise that a first cause and supreme good exists.
However, there are limits to what reason alone can discover. It cannot reveal God's inner life, his mercy or his plan of salvation. To know God personally as Father, Son and Holy Spirit, we depend upon his loving and free self-revelation in history, which culminated in Jesus Christ.
Sources
- Catechism of the Catholic Church, paragraph 36
- Romans 1:20
Awaiting review by the chaplaincy. Written in our own words; the Church's own texts are the authority.