"If there is not God, then everything is permissible." - Dostoevsky
This quote is based on the idea of objective morality, which seems to be a foreign concept to many people today. Today, more and more people are trying to take the stance that morals are subjective - right and wrong are now relative. These morals are relative based on an individuals' culture, beliefs, upbringing, and society. The problem with saying that morals are subjective is that such actions as murder, rape, theft, and lying cannot then be called "wrong." Why? Because in subjective morality, morals are simply in the eye of the beholder; there is not an objective standard by which to measure good and evil.
The existence of God however, an eternal, all-powerful, perfect being, would serve as an objective standard to judge what is good and evil. God is the object of morality. With God, everything is not permissible. There is an ultimate authority upon which certain actions, words, and deeds can be judged.
The following video shows these principles in conversation on the street: