By John Blake, CNN
(CNN) - David O'Brien couldn't help himself. After the September 11 terrorist attacks, he became obsessed.
O'Brien read the stories of 9/11 victims over and over, stunned by what he was discovering.
He read about the firefighters who marched up the smoke-choked stairwells of the World Trade Center, though many knew they could die; the beloved priest killed while giving last rites as the twin towers collapsed; the passengers on hijacked planes who called their families one last time to say, "I love you."
"I was obsessed with these stories," says O'Brien, a Catholic historian at the University of Dayton in Ohio. "There were so many stories of self-sacrifice, not just by the first responders, but by people fleeing the building. There was this revelation of goodness."
O'Brien saw an Easter message in 9/11 - good rising out of the ashes of evil. Yet there were other religious messages sent that day, and afterward, that are more troubling, religious leaders and scholars say.
The CNN Belief Blog covers the faith angles of the day's biggest stories, from breaking news to politics to entertainment, fostering a global conversation about the role of religion and belief in readers' lives. It's edited by CNN's Daniel Burke with contributions from Eric Marrapodi and CNN's worldwide news gathering team.