This is Part Four of Mark Shea’s eight-part series on the first line of the Creed. Click here for Part One.
To be sure, there are those who painstakingly make their way to belief in one God via the route of philosophical argument.
Indeed, we meet some of these people in the pages of the New Testament, where they are known by the technical title of ‘God-fearer’ (cf. Acts 10:2; 22; 13:16; 26).
These were formerly polytheistic Gentiles who had come to believe in the one God of Israel and who were in various stages of seeking initiation to Judaism.
Many of them (Luke is likely one) then became convinced that Jesus was the Messiah Israel had been awaiting and went on to become some of the earliest Christians.
Others, like the Philippian Jailer (Acts 16:25-40), may have come to monotheism, not by believing first in the one God through the witness of Jews, but by coming to belief in Jesus and then, through him, to belief in God the Father.
And some, like C.S. Lewis, come to a purely rational conviction in the existence of God, not as the fulfillment of their hopes and desires, but with dread bucking like a wild horse against the testimony of their reason:
You must picture me alone in that room in Magdalen, night after night, feeling, whenever my mind lifted even for a second from my work, the steady, unrelenting approach of Him whom I so earnestly desired not to meet. That which I greatly feared had at last come upon me. In the Trinity Term of 1929 I gave in, and admitted that God was God, and knelt and prayed: perhaps, that night, the most dejected and reluctant convert in all England.
Of course, these days most people, if they come to a belief in the supernatural from atheism do not struggle a great deal with the question of polytheism vs. monotheism. Those who leave materialist atheism for supernaturalism nearly always move immediately to belief in the one God of Abraham. But the time may not be far off that the Church will need to address the sincere difficulties of polytheists again as paganism, with its varied cults of sundry gods and spirits, makes a resurgence.
Whatever the case, to atheist and polytheist alike, the Church makes the same argument: “By natural reason man can know God with certainty, on the basis of his works.” (CCC 50). This goes right back to the roots of apostolic teaching when Paul says:
Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made. So they are without excuse; for although they knew God they did not honor him as God or give thanks to him, but they became futile in their thinking and their senseless minds were darkened. Claiming to be wise, they became fools, and exchanged the glory of the immortal God for images resembling mortal man or birds or animals or reptiles. (Romans 1:20–23)
His point is that we can, just with our wits and without supernatural revelation, know that the one God exists merely by looking around at the world.
How? The Catechism tells us that natural (as distinct from supernatural) evidence for God, knowable by human reason alone, is presented to us every day in the form of two basic things: the physical world and the human person (CCC 27).