As a card carrying pagan the imagery of both yule & ostara is very much been "borrowed" by the christians for their celebrations.

The yule log, the colour schemes etc are all pagan based. It is the celebration rebirth of the Sun, which is the promise of spring and life even on this the darkest day. It is also sometimes celebrated as the rebirth of the Great God (the sun).
Also known as: Yuletide, Alban Arthuan, Winter Solstice marks the longest night of the year. It is from this point that the days begin slowly to become longer and longer. The sun is at its most southeastern point over the Tropic of Capricorn in the northern hemisphere and has no apparent northward or southward motion. In the time of the ancient tribes this was a time of celebration, for it meant the turning point of winter and the eventual return of spring. Yule is the time when we honor the Goddess for giving birth to the sun once more. It is the time when the Oak King is victorious over the Holly King. The Holly King represents death and darkness that has ruled since Samhain, and the Oak King represents rebirth and life. The waning (diminishing) sun is overtaken by the waxing (increasing) sun, thus the days become longer after the victory of the Oak King.
The rebirth theme is very much ostara, as well as the symbolism of eggs, chicks, rabbits etc. It is a time for planting and celebrating the first signs of fertility and rebirth.
Vernal or Spring Equinox, the Rites of Spring, Lady Day, Alban Eiber and Bacchanalia.The Spring Equinox occurs between March 19th and 21st. Ostara marks the day when night and day are equal and balanced. The Sun God's strength increases. The Maiden celebrates her fertility. Ostara, her symbol the egg and her animal the rabbit, is the Norse Goddess of fertility, and it is Ostara that is honored this day. Life begins anew at this time. This is a time to plant the seeds of our flower, herb and vegetable gardens.
Also the Devil/Satan is a Christian "creation", (most) Pagans believe in a system of duality, of male/female, good/evil - balance.