In it, Murad is wearing the nun habit she wore for 13 years. The only visible skin is on her face and neck, from which a big cross dangles. Her smile seems genuine. 

What the image doesn't show is uncertainty — it was taken about 50 years ago when Murad, a Franciscan nun then living in New Jersey, started losing her faith.

"Doubt. In that photo, that's around the time I first started doubting," Murad said. "It was the beginning of who I am today."

The 73-year-old is an atheist who helps lead the secular group Humanists of the Treasure Coast. She also is a member of the Freedom from Religion Foundation, in which she is an activist against what she believes are violations of separation of state and church.

Murad has fought against Amendment 8, a measure on the Nov. 6 ballot that aims to allow religious organizations to receive state money.