The Anglo-Saxon conversion was very difficult for Christian missionaries due to the fact that paganism was so entrenched into their culture. As one of the last Barbarian groups to the converted by Christian missionaries, the Saxons did mainly under the threat of death by Charlemagne and with some great inclusions of pagan culture and concessions on the part of the Christian missionaries.
Unsurprisingly, comparisons would be made between the new Christian god and the Old Pagan ones. Besides many naturally occurring parallelisms occurring in the mythologies of Christianity and Paganism, Missionaries made efforts to render Christianity in a way that would be more pleasant to Pagan converts.
Wodan holds a high place in Anglo-Saxon theology. Expectedly, Wodan was in the first place equated by Christian missionaries with the devil. However, Anglo Saxons made obvious connections with their old God Wodan and new one Jesus. In Saxon mythology, Wodan gained knowledge of runes by sacrificing himself to himself, hanging and fasting on the World tree Yggdrasill just as Christ was also a Hanging God sacrificing himself for redemption. Christ and Wodan are also both famously mentioned in the much discussed Anglo Saxon �Nine Herbs Charm� which was a Christian charm meant to fight poison but had pagan origins. Christ was supposed to have invented the nine herbs as he hung on the Cross. As Wodan masters the magic runes of wisdom by hanging on his Cosmic Tree, so Christ creates the magic herbs as he hung on his Tree, the Cross.
Adonis, the Syrian god, was also born of a virgin. He was killed, and rose again in the spring. Every year the maidens wept for Adonis (Ezekiel 8: 14) and then rejoiced over his resurrection. This reminds us of Easter celebrations.
Bacchus, sometimes referred to as Dionysius, was born on the 25th December. The world was enveloped in evil, so the God of gods was beseeched to redeem mankind. The prayer was accepted by Jupiter who declared that his son would redeem the world from its misery. He promised a liberator to the earth, and Bacchus came as a Saviour. He was called the only Begotten Son.
Dr. Frazer in his book �The Golden Bough� (Chapter 4, p. 229) records Bacchus as saying: �It is I who guide you; it is I who protect you, and who save you; I who am the Alpha and Omega.� Bacchus was also a great traveller and brought the gift of wine to mankind. This brings to mind the miracle of Christ when he converted water into wine at the marriage feast.
Thus, it becomes clear that the core of Christian dogmas were made up from direct pagan infusions. This goes on to reinforce my position that Christianity isn�t just polytheistic, but also paganistic.
As for Christmas celebrations, this is just too well known and you may check Is Jesus really the reason for the season? (1) and Is Jesus really the reason for the season? (2) for further info.