How is this different from the claims of Christian faith-healers? I have heard plenty of essentially identical bunkum from them, claiming that disease can be cured if you only pray hard enough and have enough faith.
The innocent-victim argument surely falls as heavily on them as it does on the psychic quacks. "Negative thinking" is not that much different from "Lack of faith".
Interesting that Howard Davis ignores this topic completely.
Certainly there are some who claim to be Christian that may take this tack. In fact, they may be practicing "The Secret" and not realize they've been deceived.
But I believe that most Christians when it comes to healing through prayer know that any healing comes at or on God's timeline, not our own. Instant miracles may happen, but God may withhold healing for reasons only he knows.