As someone who grew up in a religion-free home, but nonetheless celebrated Christmas and Easter, I've long been puzzled by the difficulty many - even fairly nonreligious people - have in seeing them as secular holidays grafted onto religious ones. Christmas was about trees and Santa and presents. Easter was about chocolate bunnies and colored eggs. While both have their roots in religious traditions, the secular traditions easily exist independently. So, for holiday
displays on public property, trees and lights are fine but nativity scenes and crosses aren't. It really isn't that complicated.