I'm no expert on religious history, or on comparative religion, but I'll just add my two cents anyway... As for my own experience of Christianity, it doesn't seem to claim complete separatism from its pagan roots. Undeniably human history and culture will always have some effect on religion and its celebrations. We all live in the same earth, all cultures relate to the natural substances and seasons, which is why images and rituals involving the 'earthly' substances are very present in, I would say, (though I'm not an expert) all the different religions. Doesn't it make sense to use what everyone is familiar with and can comprehend, such as light, water, changing of seasons, growth and harvest to best help people explain religious concepts? The way I perceive it is that Christianity was able to use existing celebrations to help explain new concepts, rather than trying to be completely foreign. And while I know that colonising cultures often (probably usually) disregarded the existing people's culture/ religion in an attempt to enforce their own upon them, there are also examples of where the 'new' 'imported' religion somehow blends into the existing belief/ spiritual understanding. For example, here in New Zealand, the Maori culture is one very spiritually connected with the land. There are several Gods in Maori spirituality, of the sky, earth, forest, sea, etc. Ok, New Zealand, like all colonies, doesn't have a squeaky clean history in race-relations, but out of it all has emerged a form of Christianity which is specifically Maori 'Ratana', and which springs from a Maori way of thinking. Surely everyone will have a slightly different take on life, God, meaning etc dependant on their cultural history, so isn't it important to base religious concepts on things that people understand from their cultural history to promote understanding of the ideas? Anyway, I'm not sure if that is relevant. But basically I don't see that anyone is arguing against the fact that Christian celebrations fall on pagan dates and celebrations. So you could reduce it down to saying that Christianity just added a 'Christian spin' to pagan events - but in the end it is this 'Christian spin' that is the important part of Christianity - not what date things are celebrated. Like bandit said, Christians celebrate the birth of Christ, they celebrate the death and resurrection of Christ, this is what is important, not necessarily what date it happens to be celbrated on.