Knowing God By Reason?

[Byzantine]

What's meant when various sources say we can know God by reason? Do they mean His existence only or more?

[carmenchristi]

We can know His existence by reason, but we can also know about His love through the historical Jesus and through the Lord-liar-lunatic argument determine that Jesus is God and therefore we could reason that Jesus' teachings must be true.

[cappie]

Following Tradition, which has its roots in Sacred Scripture of the Old and New Testaments, the Church, in the nineteenth century during the First Vatican Council, recalled and confirmed the doctrine on the possibility with which the human intellect is endowed to know God through creation. In our century, the Second Vatican Council recalled this doctrine anew in the context of the Constitution on Divine Revelation (Dei Verbum). This takes on great importance.

Divine revelation is indeed at the basis of faith, of man's "I believe." At the same time, the passages of Sacred Scripture in which this revelation is found, teach us that man is capable of knowing God by reason alone. He is capable of a certain "knowledge" about God, even though it is indirect and not immediate. Therefore, alongside the "I believe" we find a certain "I know." This "I know" concerns the existence of God and even, to a certain extent, his essence. This intellectual knowledge of God is systematically treated by a science called "natural theology," which is of a philosophical nature and springs from metaphysics, that is, the philosophy of being. It focuses on the knowledge of God as the First Cause, and also as the Last End of the universe. These questions, as well as the vast philosophical discussion connected with them, cannot be examined within the limits of a brief instruction on the truths of faith. Neither do we intend to take up here in a detailed way those "ways" that guide the human mind in the search for God (the "Quinque viae" [five ways] of St. Thomas Aquinas). For this catechesis of ours, it is sufficient to keep in mind that the sources of Christianity speak of the possibility of a rational knowledge of God. Therefore, according to the Church, all our thinking about God, based on faith, also has a "rational" and "intellective" character. Even atheism lies within the sphere of a certain reference to the concept of God. If it denies the existence of God, it must also know whose existence it is denying.

It is clear that knowledge through faith differs from purely rational knowledge. Nevertheless God would not have been able to reveal himself to the human race if it were not already naturally capable of knowing something true about God. Therefore, alongside and in addition to an "I know," which is proper to man's intellect, there is an "I believe," proper to the Christian. With faith the believer has access, even if obscurely, to the mystery of the intimate life of God who reveals himself.

One Can Know God By the Natural Light of Human Reason Pope John Paul II
General Audience March 20, 1985