The key I think is that "god" is supposed to be the epitome of what is good, thus if we are unable to perceive a being with such properties in our lives or cannot believe the universe to be the creation of such a being, we may think along the lines of the famous argument attributed to Epicurus:
"Is God willing to prevent evil, but not able?
Then he is not omnipotent.
Is he able, but not willing?
Then he is malevolent.
Is he both able and willing?
Then whence cometh evil?
Is he neither able nor willing?
Then why call him God?"
And consider also the Euthyphro dilemma (in Plato's Euthyphro dialogue - although Plato himself may not have been Delta!): "Is the pious loved by the gods because it is pious, or is it pious because it is loved by the gods?"