On March 6, a billboard promoting atheism was erected in Harrisburg, Penn. Not more than 24 hours later, vandals had ripped away more than half the sign.

Today, the message is completely gone; it its place is an advertisement for the Harrisburg Symphony Orchestra.

American Atheists, the organization behind the billboard, is no stranger to controversy. They have placed similar billboards along roadsides in several states, and the signs never fail to illicit vehement responses. But this time, it was about more than just religion -- many found the Harrisburg sign racially offensive.

The billboard was dominated by a line of text reading: Slaves, obey your masters. It included an etched drawing of an enslaved man wearing a four-pronged iron collar. The line is attributed to a biblical verse, Colossians 3:22, and smaller text to the left reads: This lesson in Bronze Age ethics brought to you by THE YEAR OF THE BIBLE and the House of Representatives.

This sign, a joint effort by American Atheists and another organization called PA Nonbelievers, was meant to protest a resolution passed by the Pennsylvania House of Representatives on January 24, which declared 2012 The Year of the Bible.

After considering the bill, we thought it necessary to highlight one of those teachings and share it with the public in the form of this billboard, said a statement in the PA Nonbelievers website. Our country's history is in fact built on the moral achievements of great men and women, religious and non-religious alike. We encourage the House of Representatives to remember that when they pass laws, they are passing laws for all Pennsylvanians, both Christian and non-Christian. We humbly suggest it could start by re-considering and ultimately rejecting HR 535.

After controversy erupted, Brian Fields, president of PA Nonbelievers, offered an apology via the Huffington Post. I want to say that I'm truly sorry that many people have misunderstood this billboard, he said. It was never our intention to use race as our message itself.

American Atheists adopted a stronger tone in response to criticism. While we certainly respect the opinions of those who disagree with our tactics, we respectfully disagree with that opinion, said a statement on their website. We are unapologetic about the billboard and stand behind it 100 percent. There will be no apology from American Atheists for saying what needed to be said: sometimes the truth is offensive.

The organization plans to continue with its billboard campaign to raise awareness and spark more discussions.

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