Where is your proof that religious laws preceded secular laws?
"Stealing is wrong" is something a parent teaches the average wayward child.
...long before a priest proclaims "God forbids stealing".
Do you really think prehistoric people had to go to the priest to know that stealing was wrong?
Even a dog shows remorse when caught in the act of stealing. Do dogs have priests and invisible gods that tell them not to steal because it is against God's religious law?
Do you think a dog's conscience is usually sufficient considering they seem quite godless. Dogs don't pray several times a day in the name of Jehovah, Allah or Jesus. They don't go to church and they don't know how to read the law tablets of Moses. They cannot understand Jesus' blood... It seems dogs can't comprehend God at all..
But a dog can know that stealing is wrong. Thou shalt not steal.
All that is required to follow these "secular" laws is common empathy, not the fear of God.