The lightning strike set the statue ablaze around 11:15 p.m. Monday, Monroe police dispatchers said.
The sculpture, about 62 feet tall and 40 feet wide at the base, showed Jesus from the torso up and was nicknamed Touchdown Jesus because of the way the arms were raised, similar to a referee signaling a touchdown. It was made of plastic foam and fiberglass over a steel frame, which is all that remained Tuesday.
Church officials said they didn't know exactly what prompted the nickname commonly used by people in the area. The nickname is the same used for a famous mural of the resurrected Jesus that overlooks the Notre Dame football stadium.
The fire spread from the statue to an adjacent amphitheater but was confined to the attic area, and no one was injured, police Chief Mark Neu said.
Estimated damage from the fire was set at $700,000 -- $300,000 for the statue and $400,000 for the amphitheater, Fire Capt. Richard Mascarella said Tuesday.
The Ohio State Highway Patrol was at the scene Tuesday to prevent traffic jams and potential accidents from motorists stopping along the highway to take photographs.
Some people were scooping up pieces of the statue's foam from the nearby pond to take home with them, said church co-pastor Darlene Bishop.
"This meant a lot to a lot of people," she said.
Keith Lewis, of nearby Middletown, arrived at the church around 7 a.m. Tuesday to photograph the remains for his wife. Lewis said he had viewed the statue as both an oddity and an inspiration.
Cassie Browning, a church member from Dayton, said she was driving home when she saw smoke and noticed the statue was missing.
"It meant so much to so many people," Browning said.
Travelers on I-75 often were startled to come upon the huge statue by the roadside, but many said America needs more symbols like it. So many people stopped at the church campus that church officials had to build a walkway to accommodate them.
Bishop said the statue will be rebuilt.
"It will be back, but this time we are going to try for something fireproof," she said.
The 4,000-member, nondenominational church was founded by Bishop and her husband, former horse trader Lawrence Bishop.
Lawrence Bishop said in 2004 he was trying to help people, not impress them, with the statue. He said his wife proposed the Jesus figure as a beacon of hope and salvation.