Taylor Benge was speaking during a CNN interview with Rick Berman.
He and his sister were part of the huge crowd enjoying the Route 91 Harvest Festival when 64-year-old Stephen Paddock sprayed bullets into the concert goers from the 32nd floor of a nearby hotel on the Las Vegas Strip.
Benge said in the midst of the chaos he remembered people "laying in pools of blood" and his sister throwing herself on him to protect him.
He added: "It's a kind of fight or flight situation ... you've just got to take it to God at that point and hope that you make it and hope that you're safe.
"I know I can't speak for everyone, but for me... I was agnostic going into that concert, and I'm a firm believer in God now, 'cause there's no way that... all that happened, and that I made it, and I was blessed enough to still be here alive talking to you today."
Investigators said Paddock killed 59 people and planned the massacre so meticulously that he set up a camera in the peephole of his hotel room in an apparent attempt to spot anyone coming for him.
