When people in the UK celebrate, easter, halloween, christmas etc they seem to enjoy the physical aspect of these events (The eggs, the tree, dressing up as ghosts etc) but not necessarily the Christian aspects of these periods and their meanings. Most don’t seem to care about that side atall. In that case, could it be assumed that most people who may consider themselves Christian for their participation in these seasons, are actually more pagan and don’t even realise it?
I think that there are universal truths, realities and archetypes if you like, that mean that spring, summer, autumn and winter, birth, death, sowing and reaping and so on will always be celebrated by people, it’s just the way they express that is subject to the culture, technology and zeitgeist of their times. The cultural “overlay” is not so important if you ask me, it’s rather the underlying message.
Nevertheless, I’d be careful about attributing too much so-called “pagan origin” to many festivals, especially Hallowe’en, because on deeper enquiry it’s very often not the case or at least not as it is often made out to be. On the other hand, many once religious festivals have become very secular anyway, notably Christmas, so I don’t think a great many people necessarily attribute any spiritual side to them – be that Christian, pagan or whatever else.