[An atheist, regarding the existance of God:] There ain't no such thing, any the amount of time you spend "worshipping" and praying and sending money to him is a complete waste of your time and effort.
On the contrary, even if there is no God then the effort, time and money spend in devotion to God or Gods is not wasted. It fulfills an important human need, and all people need to acknowledge and have some respect for that demonstrably universal and immutable aspect of human nature, including the need for spirituality in their own lives.
Why must this aspect of human nature be acknowledged? Because if one form of its expression is stamped out or suppressed then it will just surface in another way, perhaps in a way that is more irrational and counterproductive.
One example of this is that liberals who say that they are atheists usually have an irrational quasi-religious political idealism that makes dialogue and compromise impossible, rendering society and political life more unstable, more prone to extremes.