The Secular Humanists of the Lowcountry ... says it has no intention of turning believers into non-believers with this campaign. Instead, they want those who do not believe in a supernatural being to know that there is a happy and welcoming community of other-like minded people.
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See also:
New atheist billboard goes up in Charleston, SC
Don't Believe In God? You Have a Billboard
Humanists' billboard to greet drivers on interstate
Godless billboard to go up along I-26
The secular humanists start a billboard campaign
Pro-atheism ads will hit South Carolina next