Every so often I reach irritation saturation with the "Christian holiday" thing and post an elementary guide to syncretism. You're lucky this year; I'm keeping it simple!
Saturnalia - Roman (as in Zeus, Hera, etc) winter festival of food, booze, gifts and partay. Late December. All other cultures in wider Europe had a midwinter festival, too. In agriculture, winter was the holiday time - nothing growing, just a few animals to feed - and so people liked to kick back, share their stored produce, and light things up to relieve the darkness.
Easter - Spring festival, as represented by Ishtar (posted by a PP), celebrating the return of life and fertility. Everything's started growing again, the birds & animals are shagging: all of Europe starts looking forward to a bountiful harvest. And squeezes in one last party before the real work begins.
Christianity - Isn't stupid. Like every major religion, it knows better than to try & rob people of their fun while converting them. Adopts the winter festival as Christmas (if there was a Jesus, he was born in March apparently.) This way, everyone gets their lights, feasts & presents but now it's a feast of Christ. Fine. Easter - easy! Return of life, Christ gets murdered and returns. Hurrah, let's celebrate. Have a party :)
Easter is a secular, pagan and christian celebration. - Fourage is correct.