Here's a good editorial explaining why it's not a tragedy for Santa Monica to have its nativity scenes relegated to private property, and pointing out that it's not only atheists who find such displays on public land inappropriate:
"The First Amendment includes two key clauses. One protects the right of every American to the "free exercise" of his or her religion. The other prohibits a government "establishment" of religion. Together they reflect a philosophy that has served us well over the past two centuries: that the best protection for religion and religious people is to give the individual both the power and freedom to practice as they choose, and to give the government neither. The idea that not having a religious display in a public park threatens religion is, to me, ludicrous. Christianity is strong enough in Santa Monica to survive the threat of a handful of atheists. There are many, many private places — shopping malls a block away, churchyards, front yards and the rest — where the birth of Jesus is celebrated."
Exactly. It's always nice to see that some people who aren't atheists "get it."