Leaders of the Roman Catholic Church in the United States and other religious denominations questioned the authenticity of the healing. In the mid-1950s, in a step that would become familiar, a group of Arizona ministers offered to pay $1,000 to anyone who had been healed by Mr. Roberts and could provide medical proof. They received no response. Still, thousands of Mr. Roberts’s followers asserted that they had been cured by his hand alone.
via www.nytimes.com
If that same $1000 offer had been for people who believed they had been possessed or harmed by Mr. Roberts, I'll bet you a lot more folks would have stepped forward. People want to believe, not be bought to not believe.
No matter your personal opinion of Oral Roberts, his generation of ministers changed religion in the US and were incredibly effective media powers.