There is much dissention on this particular topic, with both pagans and Christians taking both stances. There are many brands of Christian mysticism, some more similar to the aspects of paganism than others. But some pagans who dance outside to the light of the moon and praise the Goddess in Her aspect of Diana see and feel no contradiction to going inside and lighting candles to Mary, the Queen of Heaven and the Mother of God, the next day. And those same pagans see the same sacrificial king motif in Jesus as they do in Osiris.
Many people might find it difficult to reconcile the two paths; others see a successful integration possible. It depends on what is right for the individual.