One of the logical arguments that William Lane Craig uses in debates with unbelievers is the following:
If God does not exist, objective moral values and duties do not exist.
Objective moral values and duties exist.
Therefore, God exists.
Skeptics generally counter the argument in one of two ways. First, some try and deny that objective moral values and duties exist. However, unless one doesn’t object to babies being tortured for fun or with children being sexually abused, this assertion dies a mercifully short death.
Next, they will try and say you don’t need God to be good. In making this claim, they demonstrate a misunderstanding with the source and knowledge of moral values and duties. The moral argument for God has never claimed that atheists can’t be moral people or that they don’t know what’s right or wrong. Instead, the argument is that, without God, there is no grounding source for objective moral values and duties.
Outside of God, the only possible sources of objective moral values and duties are (1) the natural universe; (2) culture; (3) the individual. When examined closely, all fail to live up to what’s needed for objective moral values and duties.
The next presentation in the Essentials of Apologetics series looks at these issues and provides good arguments for why objective morals do exist and why that makes faith in God reasonable. The presentation can be viewed and downloaded now free of charge.