I sometimes read that Charles Darwin’s theory of natural selection, or some succeedant variation on this, was the primary cause of the rise of atheism among the elites in European society.
Yet, consider the following passage by John Herschel, one of the most prominent English astronomers of his day (Preliminary Discourse on the Study of Natural Philosophy, 1830):
“Nothing, then, can be more unfounded than the objection which has been taken, in limine, by persons, well meaning perhaps, certainly narrow-minded, against the study of natural philosophy, and indeed against all science, – that it fosters in its cultivators an undue and overweening self-conceit, leads them to doubt the immortality of the soul, and to scoff at revealed religion. Its natural effect, we may confidently assert, on every well constituted mind is and must be the direct contrary.”
Herschel’s book was written well before Darwin’s On the Origin of Species was published (1859). That he felt a need to spend a significant part of the first chapter of his book arguing for a “natural philosophy” -> “certain received religious ideas” link seems to suggest that he thought it a serious issue, despite his ostensible beliefs about their complementarity.
This suggests that the rise of atheism among the scientific elite started prior to Darwin’s theory. This further suggests that the cause of the rise in atheism after Darwin was in some sense part of the same cause, whatever the proximate causes may have been.