Re Santa's connections to Odin, many pagans see Odin as a precursor to Santa, and not without reason. From Wiki:
^The god Odin's role during the Yuletide period has been theorized as having influenced concepts of St. Nicholas in a variety of facets, including his long white beard and his gray horse for nightly rides (see Odin's horse Sleipnir), which was traded for reindeer in North America.[18] Margaret Baker comments that "The appearance of Santa Claus or Father Christmas, whose day is 25th of December, owes much to Odin, the old blue-hooded, cloaked, white-bearded Giftbringer of the north, who rode the midwinter sky on his eight-footed steed Sleipnir, visiting his people with gifts. … Odin, transformed into Father Christmas, then Santa Claus, prospered with St Nicholas and the Christchild became a leading player on the Christmas stage."^
Re Santa as satan, there are certainly christians who make this association, just not commonly in the uk. Have a look at this website, or maybe this quote from a baptist article:
^So talk to your children before it is too late! Tell them that Santa is no kindly old man; he is an evil demon. And next time your family sees some propped up gin-soaked vagrant in a Mall wearing a red suit with white furry cuffs, set a good example and witness for the other deluded people waiting in line. Loudly, rebuke him! Announce to all the children in the store "Not only is Santa a lie, he will ravage you sexually, drink your blood and drag your palpating carcasses down to Hell with him!" It is only through setting a good example that we can put the Christ back in Christmas.^
I appreciate that this is not the attitude of most christians, but it is wrong to suggest that it does not exist.