Why do so many christians celebrate pagan celebrations?

Its was like a hearts and mind campaign against pagans especially in europe and the UK,when that failed,and it did they used the usual method of usurping pagan holy sites,desecrated the circles and groves,murdered 12 million people and then said unless we followed their ways we would be condemned to hell and helped on our way by their "holy orders",the gods in the UK we worshipped never survived in any large grouping and all the "rituals" have been lost in time...so they like governments and politicians of the day use deception and brute force to achieve the same goal...domination and suppression and that is how christians partake of pagan rites and holidays,imilate and annihilate...that is their doctrine.