If someone says to you "There is no God", firmly respond saying "There is a God indeed, yet for you He does not exist."
It would be more accurate for an unbeliever to humbly say, "I have no God", since the majority of people do acknowledge belief in God and consider it a statement of utter arrogance to assert that one could come to an absolute belief that God does not exist.
When an unbeliever dogmatically states "There is no God",...:
... it is like a sick person saying that health does not exist.
... it is like a blind person saying there is no vision to see light.
... it is like a beggar saying there are no riches in the world.
... it is like an evil man saying there is no goodness among men.
Rather,...:
... the sick person should say "I have no health".
... the blind person should say "I have no vision".
... the beggar should say "I have no riches".
... the evil man should say "I have no goodness".
Just because someone doesn't have something or doesn't understand something or doesn't believe something, it doesn't mean everyone lacks what they lack. So instead of an atheist dogmatically stating his lack of God should be lacked by everyone, he should acknowledge his lack is merely only a personal loss compared to those who do believe in God and live a fuller and richer life because of it.