I was brought up without religion. For as long as I can remember, my mother always insisted she would "let me decide about such matters when old enough to make up my mind". By choosing to bring me up this way she broke new ground – I am part of the first generation of my French family not to get baptised and not to be enrolled at Sunday school. My family seems to have gradually lost faith, or at least lost any sustained interest in it, during the past 25 years.

At no point did my mother ever discourage me from exploring faith systems. We would visit churches, and she'd answer any questions I would have. I was taught in school, at length during my history classes, about Christianity, Islam and Judaism. But I never found any need for God. I recently developed a healthy enthusiasm for the Society of Friends, and enjoy reading about small factions of believers such as the Mennonites, or the Amish. But I remain an atheist, and my core political beliefs are resolutely secularist.

Thinking back about my relationship with religion, two memories stand out. In the first, I am spending a Saturday afternoon at my neighbour's house. He's my best friend, and we are no older than 10. His is an observant Catholic-Portuguese family, his parents having immigrated to France during António de Oliveira Salazar's dictatorship in the 1960s. We're upstairs in his sister's bedroom, when a part of a necklace we were admiring drops and rolls under the bed. We rush to the floor to look for it, without much luck. Panicked, my friend exclaims: "Well, we have to pray to Saint Antoine de Padoue. That will help!" I raise an eyebrow, and he explains that the saint in question "helps you find lost things" – and that his family prays to him often. Having never heard of him before, I just think it's another of his quirky family's antics.

The second anecdote takes place little less than a year later, when another close friend shares her excitement following her confirmation. She tells me about the day she spent with other kids from our class and their families, and how nervous she felt beforehand. What struck me then, however, was the long list of presents which followed, proudly enumerated by my friend: "jewellery, a lot of sweets, a lot of money from different family members, clothes and, best of all, a brand new CD player" (CD players were quite the new thing at the time). "And you got those just for going to church?" I asked, not without a tinge of jealousy. "Pretty much," she replied.

Soon after confirmation, hormones and school crushes replaced Sunday school for most of my friends, who didn't set foot in a church for years afterwards. I suppose it was felt that baptism, communion and confirmation were things that "had to be done", but church attendance beyond those events wasn't enforced. Parents rarely went to church themselves once their last child was confirmed; the strict minimum had been completed.

Of the vast majority of my classmates at the time, my neighbour is one of the few who remains an enthusiastic believer. But his – and his parents' – faith wasn't affected or constrained by what my young mind interpreted to be appearances or external pressures. Their faith just is. It is earnest and accompanies them all week long, not just on Sundays, in everything they do. It was noticeable from the crucifix in my neighbour's bedroom, to his mother's endearing superstitions and the epic tales about his father completing pilgrimages (he had once even walked the last 200 metres to the Chapel of Apparitions in Fatima on his knees, as custom requires. I was told it hurt quite a bit, and remember being in awe of that – without completely understanding it).

The fact that his family originated from a country with far stronger Catholic roots than in France, which, as part of its history boasts a bloody revolt against clerics as a high point of its political foundation, surely played an important part in their faith's vibrancy. Religion in Portugal strikes me as part of the very cultural fabric of the country, whereas pride in any belief in France is seldom shouted from the rooftops.

The last time I talked to a young person who was proudly practising was at university; she was a very stereotypical conservative student with a very bourgeois upbringing, who had been to Catholic summer camps throughout her teenage years – a true rarity. The rest of the people with a religious background that I knew were either lapsed Catholics, agnostics, or very much kept their belief to themselves. Their parents gave up on churchgoing and Bible studies long ago, too busy paying the bills to find the time for devotion. It just skipped their minds.

As to the question, "Is God disappearing?", I can only think that French Christianity is indeed fading because it is upheld by families whose hearts are not deeply committed to it as part of their heritage. I'm not sure it is a bad thing, either: why keep up half-baked social pretences just for the sake of it?

I recently asked my beloved grandmother, who is in her mid-90s, whether she still believed in God. She hesitated, and said: "Not really … but when I am gone, I still want a religious burial." I suppose that some cultural attachments to tradition are deeply comforting and will remain. I doubt those will still exist a few generations from now.