American Atheist president David Silverman said Monday that a series of billboards recently purchased by his group were meant to show non-believers why they needed to organize.

"A lot of people say, 'Well, why do I need to get involved? Why do we need an atheist movement?'" he said on The David Pakman Show. "Well, we need an atheist movement because we have an anti-atheist movement in this country that is actually set on making atheists second class people. This is not something for which we should stand and it is certainly not something for which we should stand even if it is done in the name of religion. It's not OK if somebody is a bigot or somebody is hateful because the Bible says he should be. He is still immoral."

Silverman noted that former House Speaker Newt Gingrich (R) said during a 2011 Republican presidential primary debate, "How can I trust you with power if you don't pray?" Silverman said the statement was an example of religious bigotry.

"When Newt Gingrich comes out and basically says I can't trust atheists, that's a horrible, bigoted, backwards, primitive thing to say," he continued.

"And it is not something that should be excused and it is not something that should be OK because it is a part of his faith. He is a bigot and he is using his faith as some sort of a shield against criticism of his bigotry."

The American Atheists has purchased seven billboards in Texas that target Gingrich, former Alaska Gov. Sarah Palin (R), former Pennsylvania Sen. Rick Santorum (R), Pope emeritus Benedict XVI, and Dallas Pastor Robert Jeffress.

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