When the source of all truth is rejected, a ruling truth for society is hard pressed to keep moral order. Justice fails. There is nothing upon which to build a standard for right living. There is no public commitment to truth, and those who live to please God will find themselves out of the discussion in the public square.
This was the situation that marked the lives of the citizens of Jerusalem just before God's judgment came in the fire and the swords of the Babylonian army. The people of God had long abandoned God's Law as the objective truth around which to build their society. And the chaos that ensued ultimately led to their destruction. When there is no truth, righteousness cannot be known. When truth stumbles, everyone will fall down.
It would be easy to complain that truth has stumbled in the public square. But as long as there are people of God in this world, it does not have to be that way. We can stand uprightly, and winsomely to the watching world. We can still live the truth and demonstrate the change that the gospel brings. The worst thing that we could do is resign ourselves to fallen truth, watch as injustice rules, and do nothing... comforting ourselves with theology. Instead, truth must be lived in us, even as it is rejected by others. We must love our neighbor and our God -- publically, so that truth can pick itself up and stand again!