Legality has nothing to do with morality. What morality is there in saying that you cannot pass a vehicle in a tight lane? None. It's a safety concern. Morals only concern religion. Ethics concern right or wrong. Law concerns a group of defined social agreements between people within a defined region. While the basis of some of our laws has a history of Christian influence, our laws in and of themselves do not require morality. An atheist is no more likely to go on a murderous rampage than a Christian, ethically it would be wrong. That kind of timing is built into humanity as a whole because it's required for civilization and predates religion. You see it in animal species as well. Heck a dog sees the benefit in not murdering their master.