Brian "Sapient" is an average-looking 30-year-old guy who works out of his basement in Philadelphia. His job? Well, Brian is taking on God.
"Wow, that's a dramatic way of putting it," says Brian, who asked that "Nightline" not use his real last name for safety reasons. But however he defines his challenge, Brian is on the cutting edge of a new and emboldened wave of atheism.
"There isn't any good reason to believe in God," asserts Brian. "It's that simple."
What's wrong with God?
"What's wrong with the tooth fairy?" asks Brian. "There's nothing wrong with something that most likely doesn't exist."
There are an estimated 20 to 30 million atheists in the United States these days, and some of them say they feel like a persecuted minority.
"Atheists are completely vilified. And it's OK," says Kelly, an atheist who works alongside Brian and also asked that her last name not be used.
"It's actually OK to hate atheists," Kelly said. "We are like the last group that people overwhelmingly agree that it's OK to hate us, because there's an absurd caricature of atheism out there."
Brian and Kelly are co-founders of the Rational Response Squad. From Brian's basement they broadcast a weekly Internet radio show about God or the lack thereof.
And recently they came up with a new way to publicize their cause. It is called the Blasphemy Challenge.
"Initially we wanted to find a way to allow atheists to come out of the closet, speak up and show other people that there are people that think like this," Brian says.
What they did was challenge people to make videos of themselves, denying, denouncing or blaspheming the Holy Spirit, and then post them on YouTube.
"We wanted to do it in such a way where we stripped the power from religious institutions that instill fear in people," says Brian. "And we did that by blaspheming the Holy Spirit, by showing that we are not scared of this unforgiveable sin."
A passage in Mark 3:29 reads, "whoever blasphemes against the Holy Spirit will never be forgiven; he is guilty of an eternal sin."
While the passage is open to interpretation, the Rational Response Squad is taking it literally and challenging people to gamble with their eternal souls. So far more than 800 people have taken up the challenge.
One of the posts is by a young-looking man named Chandler. He says: "I've come to the conclusion that alongside the fact that there is no Santa Clause and there is no Easter bunny, there is also no God. So, without further ado, my name is Chandler and I deny the existence of the Holy Spirit."
Another: "My name is Joel. I deny the Holy Spirit, as well as God, Jesus, Buddha, Zeus, Mohammad, Joseph Smith, Sponge Bob, the pope, Santa Clause, Mother Mary, the Easter bunny, the tooth fairy, Optimus Prime, all the saints and Spiderman."
Dozens upon dozens have posted, including comedian Penn Jillette, who simply says, "I deny the Holy Spirit."
"I think how sad it is that someone would be rejecting hope essentially," says the Reverend Kathleen Liles, an Episcopalian minister, just one of many from the religious community who say this Internet challenge is misguided or worse.