Evidence for a standard of morality is everywhere: we see it in every culture, age group, and time in history. Even some of the most staunch moral relativists cannot deny the presence of a standard of morality--they openly criticize the evil we see in the sex trade, holocaust, slavery, child abuse, domestic violence and genocide that wreak havoc on our world.
The presence of this evil points to the existence of good; without good "evil" is a meaningless concept, just like the term "dark" only makes sense because we have experienced something we call "light". Now, if "good" and "evil" are meaningful ideas in our world then we must ask the question, who determines what is good and what is evil?
Obviously we can't attribute this standard of morality to past presidents, kings, or dictators who somehow convinced the entire world to jump on their moral bandwagon. Some people argue that morality has evolved over time to promote human flourishing. But one has to wonder, if the origin of morality is a desire for human flourishing, from where does our concept of human flourishing originate? Not only that, how do we explain values like justice, love, diligence and responsibility that transcend time and culture?
Others appeal to science to rationalize our knowledge of good and evil. The strict materialist tries to explain away moral convictions as the movement of particles or chemical reactions in the brain. With this explanation our moral sentiments and convictions are no more meaningful than the convictions a fizzy cup of vinegar and baking soda might have. Hence, the materialist reduces humans to nothing more than bodies full of internal "fizzing".
The problem with the scientist's explanation is it ultimately explains away “true” and “false” statements. Thus, the scientist explains away his own explanation, for even his explanation of morality must be nothing more than the movement of particles or the "fizzing" of chemicals in his brain.
That leaves us with the presence of widely recognized evil which points to good, and nothing to explain our understanding of good and evil--except God.
"Taste and see that the LORD is good; blessed is the man who takes refuge in him." Psalm 34:8