In the Netherlands we used to have a 10-yearly returning academic study “God in the Netherlands” about what the Dutch believe. The latest version was in 2016 as far as I can find, so the numbers will be irrelevant by now, but the tendency is the same for decades: only a minority of the people in the Netherlands say they are part of any Christian denomination. Majorities of both Protestants and even more so Catholics do not go to church on Sunday anymore. Among Protestants “orthodox” belief is strongest, but even there about 1/3 doesn’t believe in the divinity of Christ. Among Catholics this is even stronger.
My personal experience, so not scientific relevant at all, as a member of the Catholic clergy in a Dutch diocese, underlines these findings. It has become very rare for Catholics to have their children baptised, to marry in Church, to come to Sunday mass, and so on.
Even if parents wish for their children to be baptised, it is very clear that most parents do not know much about the Catholic faith, and on most points do not subscribe to it verbally. It is impossible to know what people really believe, but I think it gives an indication.
So there is a very large group of Catholics, and a bit smaller but still large group of Protestants, who call themselves Catholic, Protestant, or Christian, who say they believe in “something”, “a force”, “the universe”, but definitely not in the central Christian teachings and very often not in a personal God, let alone a God in three Persons.
These people have all freedom to call themselves atheist. In the Netherlands there is absolutely no social stigma on being an atheist, there is a growing stigma on being religious. Still, this group that can hardly be described as theists in the Christian sense, wishes to see themselves as Protestants, Catholics, Christians. They feel the need to belong to this group, the need for certain rituals, and maybe some sort of sense making attached to being Christian.
(news story in Dutch: Hoe God (bijna) verdween uit Nederland)