I'm in the middle (or rather still at the start of the immensely long), A secular Age, by Charles Taylor.
Taylor's explanation and analysis of secularism is helpful, and provided an immediate backdrop this Christmas to a story from my brother, out on the high streets of the UK.
So Secularism is usually theorised and explained as a) the retreat of religion from public space, b) the decline of religious belief and practice. With a) where religion is marginalised in social life and leads to a decline in its practice relegated to the private as other social forces order life whilst b) religion sees a decline in personal faith driven by the forces of science that leads to secularistion.
Yet for Taylor, he argues that science is not neutral in a rational opposition to religion, but rests on a moral frameworks for it's appeal to non belief. Also he sees the institutional changes that move religion into the realm of the private as being subject to strong spiritual and moral forces, and it is these and not just the waning of belief that is taking place.
This allows Taylor to claim his thesis that in fact secularism has not developed on neutral grounds, but over time on deeply moral sources; such that not long ago we lived in a western world where it was almost impossible not to believe in God, to where we now live in one in which believing in God is simply one option of many.
As I dig into Taylor's account, my brother offered me an anecdote this Christmas from a recent shopping trip that seemed apposite to that reflection. It seems he and his wife were shopping in a jewellery story and overheard two young ladies comparing and reviewing the items on display. One remarked to the other, 'look at this one, it has a cute little man on it'.
My brother confirmed his suspicions on viewing the item - it was a crucifix.