See this is where some atheists (Myself not included) are stupid. That sign hurts nobody. Those who believe are comforted by it. Those who are not should just ignore it.
morality is a human concept. It is moral to shoot a robber but not a little old lady selling flowers. To kick a stray dog growling and coming at you. But not a cute puppy.
These are things learned through Thousands of years of Human interaction. Not given out by an unseen sky God or a dead Jew the Romans nailed to a stick.