It's the old story of the "cut flower" effect. When you cut morality off from its root, religion, eventually what you will have left is just an ugly flower. Old humanism lived on a Christian memory. That memory is quickly fading and we are now being left with the ugly results. Humanism, based on atheistic evolution, can't justify good morality. Natural Law and our conscience tell us that there is right and wrong, but the philosophy of atheistic humanism can't give morality a necessary foundation. It was a good article.
Chesterton wrote about naturalism. This is a paraphrase: Nature worship starts as the worship of spring, of growth, beauty, freshness. Then as it goes on, there is no reason to not worship the night as well as the day, the side of nature that is red in tooth and claw. Nature worship ends badly.
Not Paraphrased:
All the same, it will be as well if Jones does not worship the sun and moon. If he does, there is a tendency for him to imitate them; to say, that because the sun burns insects alive, he may burn insects alive. He thinks that because the sun gives people sun-stroke, he may give his neighbour measles. He thinks that because the moon is said to drive men mad, he may drive his wife mad. This ugly side of mere external optimism had also shown itself in the ancient world. About the time when the Stoic idealism had begun to show the weaknesses of pessimism, the old nature worship of the ancients had begun to show the enormous weaknesses of optimism. Nature worship is natural enough while the society is young, or, in other words, Pantheism is all right as long as it is the worship of Pan. But Nature has another side which experience and sin are not slow in finding out, and it is no flippancy to say of the god Pan that he soon showed the cloven hoof. The only objection to Natural Religion is that somehow it always becomes unnatural. A man loves Nature in the morning for her innocence and amiability, and at nightfall, if he is loving her still, it is for her darkness and her cruelty. He washes at dawn in clear water as did the Wise Man of the Stoics, yet, somehow at the dark end of the day, he is bathing in hot bull’s blood, as did Julian the Apostate. The mere pursuit of health always leads to something unhealthy. Physical nature must not be made the direct object of obedience; it must be enjoyed, not worshipped. Stars and mountains must not be taken seriously. If they are, we end where the pagan nature worship ended. Because the earth is kind, we can imitate all her cruelties. Because sexuality is sane, we can all go mad about sexuality. Mere optimism had reached its insane and appropriate termination. The theory that everything was good had become an orgy of everything that was bad.
Orthodoxy, Flag of the World Chapter