My experience of Christianity as a child (5-11 years old) was an oppressive one.
The village school was a Church of England establishment, and so Christianity was woven into its life. But while I liked many aspects of the school, and have many happy memories about it; my recollections of the Christian side of its life is almost wholly negative. It was, as I said, an oppressive experience; like a weight of life-draining deadness pressing-upon me.
I disliked assembly, being preached-at, and I disliked most of the hymns we sang - which seemed dirge-like, with nasty words; and I resisted many of the things we said in prayers. I disliked being told that God was 'my' Father when I had one already, with whom I was more than happy.
I didn't like the Bible stories, I didn't like going to the nearby church, where the words were incomprehensible and the hymns even more dirge-like when accompanied by the droning organ.
It was clear to me that there was this thing called Christianity, religion, that wanted me and everybody else to fit-into standard shapes it already had waiting for us; that there was a pattern and it was supposed to be my business to squeeze into this shape and pretend to be happy about it - despite that the shape was designed for some other, some 'average' person - somebody, at any rate, who was not me, nor anything-like.
Christianity was not interested in me, as I saw myself; me as an individual with an intense self-awareness. It just wanted me to say and do a pre-specified set of things.
And there was a clear assertion that this was what Christianity is; that this whole set of social practises, the assemblies, hymns, prayers, talks, church visits etc - was Christianity: take it or leave it. I left it.
Such are the reasons why I became an explicit atheist aged about six and - on grounds of conscience - was (intermittently) excused from RS classes (along with a Roman Catholic boy). I never saw any reason to change this decision as a child; although I was a relaxed kind of atheist, and participated in musical and social events at the church, was friendly with the Rector (priest) etc.
Such was wrong with the Old Time Religion, and such is perhaps what was intrinsically wrong with it - and perhaps why it can't ever come back: so many people don't want it back.
The modern consciousness (which we are stuck-with, for better, as well as for worst) cannot bear to be treated as something that society merely moulds-into pre-determined, standard shapes. And that is not negotiable.
Yet Christianity is true, and necessary; and the greatest possible life enhancement. Since we cannot live without it, we will have to find a way forward - a new way, or perish.