The parents of murdered photojournalist James Foley expressed pride in their son and faith in the Lord's will in a statement to reporters on Wednesday.

A graphic video of the kidnapped American's death was released online by the Islamic State (IS) on Wednesday, and the White House confirmed that the footage was authentic.

Foley's parents, John and Diane, expressed thanks for the prayers and messages of support they have received from across the globe.

"We also want to appreciate the tremendous number of prayers we've received, and Jimmy received, from all of our communities," John said, according to the Huffington Post.

"Jimmy had said in Libya, and we're very sure now, that he could feel the prayers, and we think his strength came from God."

Foley was kidnapped in Libya in 2011, and held for 44 days. He continued to cover war zones and volatile countries despite the danger he faced.

"So many people were praying for Jim," Diane said. "And I really think that's what gave Jim an unusual courage. Jim just could feel the prayers. He was strong, courageous, loving to the end... he was just a hero."

Foley, 40, was covering the Syrian civil war when he was kidnapped nearly two years ago. In the execution video, he is being held captive by a member of IS, a terrorist group that controls much of northern Iraq and Syria.

President Obama said "the entire world is appalled" by the Muslim extremists' acts in a Wednesday press conference.

"No just God would stand for what they did yesterday or every single day," he said.

The Foleys expressed comfort in knowing that their son is no longer a prisoner.

"We know Jimmy's free," John told reporters. "He's finally free. And we know he's in God's hands...and we know he's in heaven."