They err who say: “The world is turning pagan again.” Would that it were! The truth is, we are falling into a much worse state. Post-Christian man is not the same as pre-Christian man. He is as far removed as a virgin from a widow….there is a great difference between a spouse-to-come and a spouse sent away.
Hence, a worse state than the one we were in before we received the faith. For no one returns from Christianity to the same state he was in before Christianity, but into a worse state: the difference between a pagan and an apostate is the difference between an unmarried woman and an adulteress….Therefore many men of our time have lost not only the supernatural light, but also the natural light which the pagans possessed.
For my part, I believe we ought to work not only at spreading the Gospel (that certainly) but also to a certain preparation for the Gospel. It is necessary to recall many to the law of nature before we talk about God. For Christ promises forgiveness of sins, but what is that to those who, since they do not know the law of nature, do not know that they have sinned? Who will take medicine unless he knows he is in the grip of a disease? Moral relativity is the enemy we have to overcome before we tackle atheism. I would almost dare to say, “First let us make the younger generation good pagans, and afterwards let us make them Christians.”
—from The Latin Letters of C.S. Lewis by C.S. Lewis and Fr. Giovanni Calabria
—I have not read this book. I came across these passages (and commentary on them) in Monsignor Charles Pope’s blog post titled C.S. Lewis as many have never heard him.
—Read more about how this idea is being played out now in the article: Christianity and the New Paganism by Peter Kreeft