It's similar to Christmas. What in the world do Santa Claus and mistletoe have to do with the Messiah's birth? During medieval and Renaissance times, Christians incorporated certain holiday traditions from local pagans. For example, Christmas as we know it today draws a lot from Nordic and Celtic winter solstice festivals(Santa Claus is a combination of St. Nicholas and Odin Allfather). The same thing with Easter. Of course, today we decorate trees and paint eggs for the fun of it, instead of worshiping pagan spirits. The central focus of Christmas and Easter is still to celebrate the birth and resurrection of the Prince of Peace.