It's a warm fall morning near the Texas State Capitol's south steps, and there's a fight brewing.

"Don't be an idiot!" a man shouts at a small crowd making its way up toward the Capitol. He is David Stokes, a self-described "street preacher" from Houston, arrived specially in Austin for the occasion. He's in his late 40s or so, wearing jeans, a green T-shirt and mirrored sunglasses. The first thing that really draws the eye, though, is the enormous sign he's carrying.

"WARNING," it reads, in five-inch high orange letters. "Drunks, homosexuals, abortionist [sic], adulterers, liars, fornicators, thieves, atheists, witches, idolaters, HELL AWAITS YOU."

"Walk away from atheism!" Stokes cries at a couple of college-aged women. Instead, they're walking determinedly toward it, trying not to make eye contact. They make it safely past and up the leaf-lined path toward the Capitol, where they join 400 or so other atheists, agnostics and skeptics gathered for the first day of the Texas Freethought Convention.

With the exception of Stokes, the mood around the Capitol steps is festive. The crowd is set up in portable lawn chairs or standing on the grass in the shade of trees, listening to a tall, broad man at the podium. He's got a pencil-thin Fu Manchu mustache and the sort of hat that Indiana Jones might wear, which is keeping his nearly waist-length hair in check. He's wearing a gray suit and a bolo tie, outfitted at the throat with a black scarab beetle clasp.

Apart from the suit, he looks like a roadie for a terrifying metal band. In fact, he's Aron Ra, a popular "YouTube atheist" from Garland, with more than 60,000 subscribers tuning in each week to hear his shows.