Doctors note that sometimes people can have a psychologically induced illness, and if they get a new purpose or direction for living, they show relief from the symptoms—they don’t need the illness anymore. For some others, the “placebo effect” can have visible results. That is, if you think you’re going to get better, you often do get better. And when people came to Jesus, they believed he could heal them, so he did. But the fact remains: Regardless of how he did it, Jesus did heal them.
Of course, even if you hold to this explanation for some cases, that doesn’t explain all of Jesus’ healings. Often a psychosomatic healing takes time; Jesus’ healings were instantaneous. Many times people who are healed psychologically have their symptoms return a few days later, but we don’t see any evidence of this in the gospel accounts. And Jesus healed conditions like blindness and leprosy, for which a psychosomatic explanation isn’t very likely. In addition to these, he brought people back from the dead—and death is not a psychologically induced state! Finally, you have all of his nature miracles—the calming of the sea, turning water into wine. They defy naturalistic answers.
Adapted from interview with Dr. Gary Collins