Why does the Church keep all pagan holidays?

The Church does not keep all pagan holidays. In many cases, the Church nominated that a feast day or holy day be celebrated on the day of a particular pagan holiday, in order to make it difficult to practise the pagan festivities and to attract people more fully into the Christian faith. However, when Emperor Theodosius made Christianity the official religion of the Roman Empire, he declared that all pagan holidays that had not been adopted by Christianity were no longer to be celebrated as holidays - even though the majority of the population of empire was still pagan.