The fool hath said in his heart, There is no God. They are corrupt, they have done abominable works, there is none that doeth good.
~ Psalm 14:1 (KJV)
The fool hath said in his heart, There is no God. Corrupt are they, and have done abominable iniquity: there is none that doeth good.
~ Psalm 53:1 (KJV)
For further background on this illustrious [un]holiday, see my post from 1 year ago.
I don't know why I never thought of it before, but April Fool’s Day is perfect for atheists. What better way for atheists to spread their message that humans are easily duped than with a day celebrating surreptitious pranks?