Debate: "Is God Necessary for Objective Morality?"

In this congenial debate, Shelly Kagan defends a social contract theory of morality, according to which objective and binding moral obligations are grounded in an implicit agreement between members of a society.  William Lane Craig, on the other hand, defends the idea that morality is grounded in God. [embed]https://www.youtube.com/watch?v=4RbfIMudPaA[/embed]