I think with both Paganism and Christiananity what brought them together was Symbolism. Pagans used symbols to represent their beliefs and so did the Christians. These symbols overlapped and blended at times. Maybe by adapting to each others beliefs it made it easier for them to get along. Many of the symbols they used back then, we still use today. The Christmas tree, the Easter egg, Summer, Autumn, Winter, and Spring Soltice. We have people today that still worship the four seasons. Spring - rebirth, Summer - planting, Autumn -gathering, and Winter- death or resting. This is my interpertation of why we still to this day blend and add paganism to our beliefs as Christians.
Sorry this is so short, but I'm having puter probs & I wanted to get something sent in before my computer connection disappears on me again, it has been taking hours to get reconnected.