You have heard it said, “You can’t legislate morality.”  The truth is that we are always legislating morality. It is a qustion of whose morality?
We need to ask by what standard?  Will our families and communities be founded on the commandments of God or on the beliefs of some other system? Hinduism?  Islam - Sharia law? Communism?  Enviornmentalism?
Even atheist Richard Dawkins understands that God's way is the best way.  He said, “If I had to choose between Christianity and Islam, I’d choose Christianity every single time. I mean, it seems to me to be a fundamentally decent religion in a way that I think Islam is not.” 
Or as Francis Schaeffer put it, “Christianity is the only system of thought that is big enough to tackle the social problems of our time.”