In the Gospel of Mark, after Jesus calls his first disciples, he begins his ministry of miraculous healing and exorcism. The authors of the Gospels of Matthew and Luke copy these stories from Mark, editing them a bit as suited their particular messages. Throughout the Gospel of Mark there runs a thematic element of Jesus telling demons and people to keep his identity a secret; this is known as Mark's "messianic secret" theme. The author of the Gospel of Luke preserves the formulaic silencing of demons in his retelling of the exorcisms, probably because these texts were used in actual exorcisms, and thus the specific words and actions were ritually important. For this collection of short passages, the Gospel of Luke closely follows the version in Mark with a few minor edits. The author of the Gospel of Matthew spaces out these passages in three separate places, interspersing other miracle stories and teachings that were important to the author's portrait of Jesus. The thrust of these passages is that Jesus performed effective acts of healing and exorcism as part of his ministry.
Of course, we have lots of stories of exorcisms and miraculous healing from both before and after the writing of the gospels. Some of these stories make spectacular claims about actual people while others feature fictional healers, like the abundant ancient stories of the Greek demigod Asclepius. Faith healing has been associated with a variety of belief systems, as has exorcism, and both are still practiced to some extent in the world today. The breadth of these claims across human history offers a few choices about how one may respond in terms of belief.
One could believe that all faith healing and exorcism is to some extent true, but that would be a difficult position to maintain. Apart from many of the stories being clearly fictitious, belief in faith healing is challenged by the exposure of many frauds like Jack Coe, Kathryn Kuhlman, and Peter Popoff, and abundant scientific research has shown the ineffectiveness of spiritual healing and intercessory prayer in a medical setting. Even the American Cancer Society and the American Medical Association have published statements against faith healing, because of numerous tragic reports of people with serious illnesses who died because they relied on faith rather than medical treatment. Choosing to believe in faith healing in light of the evidence equates with ignoring reality.
It is possible that some stories are true while many are false, however. Some might choose to believe in the veracity of ancient stories that predate modern medicine, or in just the stories that paint the heroes of their particular faith in a positive light. The challenge then becomes how to discern which stories are true and which are false with no evidence. A person will obviously approach a story already committed to a belief, and the story itself will be judged by presumption rather than on its own merits. Since we do not have any verifiable, scientifically documented cases of faith healing or demon possession, there is no real support for believing in any faith healing. Although it is impossible to disprove an assertion that Jesus (and his true disciples throughout the ages) performed actual miracles while all others were mere charlatans, the available evidence suggests that actual, effective faith healing is unlikely.
There is a reason that faith healing and exorcism are lumped together in the gospel stories. The ancient world believed that many cases of illness were manifestations of demonic activity. Their understanding of biological reality was not as advanced as ours, and they wanted explanations for the things they did not understand. Demons were an easy explanation for bad things like disease. For some reason, even though our understanding of the physical world increased exponentially, belief in demons still persists. In twenty-first century books on Christian spirituality, one can still find abundant assertions that demonic activity and spiritual warfare are legitimate concerns, despite overwhelming evidence to the contrary. What is so appealing about holding on to a primitive worldview?
First of all, the evidence refuting demonic activity and possession is easy to dismiss if one believes that demons are real. If demons actually exist, they would certainly be able to fool a few scientists and doctors, after all. The belief seems far too deeply convincing to be damaged by a little scientific report. In actuality, if demons were prevalent, it would be a miracle if any scientific studies were ever replicable. If the world is constantly influenced by the supernatural, there would be no way to obtain reliable evidence about disease, or any natural phenomenon for that matter. If demons caused disease, we would not be able to create medical cures and vaccinations, unless demons are susceptible to the laws of the natural, scientifically verifiable world. And if demons are susceptible to the laws of the scientifically verifiable world, science would be able to test for demonic activity and verify which instances of disease are the result of demons and which instances of disease are caused by something else. What we know about the natural world and about the increasing efficacy of medical treatment strongly suggests that there are no demons.
There are some cases, however, that seem to fly in the face of that evidence, however. Anecdotes about an exorcism in which some supernatural event transpired, or about how prayer healed someone, or about some personal encounter with spiritual forces entice us to leave the door open for the supernatural. The more we learn, the more we realize how creative we can be when we don't understand something. Human beings are creators. When something doesn't make sense to us, we invent a hypothesis. Sometimes we test that hypothesis -- we do a bit of research, we perform a few experiments, we determine if our hypothesis really holds water. Other times, we are so satisfied with our hypothesis that we simply run with it, even when our hypothesis leads us to do real harm to ourselves or other people (as is the case in many documented exorcisms). Our belief in the supernatural, thus, is evidence of human creativity and laziness. When we take the time to investigate the things we do not understand, and we persist until we have understanding, we learn that the natural world can be bizarre and astounding all on its own, without the need for supernatural influence.
The real attraction, though, is that belief in demonic activity gives us a scapegoat. If we are constantly being assaulted by dark spiritual forces, then we have something to blame when we act shamefully. We can still beat ourselves up for giving in to temptation, but it's much easier to be a helpless victim to demons than it is to be a personally responsible human being. When our children behave in a way that we don't understand, belief in demonic activity can allow us to preserve our impression of them as innocents who need to rely on us to survive. Out of our own insecurities and fears, we might fail to provide effective medical or psychiatric care for our loved ones. If we believe that it's possible for our actions, or the actions of other people, to be influenced by external, powerful, supernatural entities, we don't have to examine our own thoughts and actions as closely. We don't have to confront the real challenges in life because we have invented imaginary challenges. While demons are not necessarily more attractive than reality, our ways of confronting demons might be more appealing than the sometimes difficult emotional work of confronting reality and taking responsibility for our own growth. Belief in demons is a crutch that hinders people from being fully engaged in their own lives.
People become addicted to things -- substances, behaviors, routines. People get sick. People commit crimes. People break their promises. People do things that harm other people. People do things they later regret. Not demons. People. Not people under the influence of demons. Just every-day, ordinary people. If a person wants to change -- if a person wants to break an addiction, treat a medical condition, keep promises, respect other people, act in accordance with a nobler inner self -- the answer is not exorcism. The answer is personal responsibility. If we confront the things within ourselves that lead us away from our own deep sense of worth, then we can more effectively be our authentic selves in the world. We can figuratively call those things our "inner demons" if we want to, but it's all just us. The lies we tell and the false beliefs we cultivate come from within ourselves, and we have the power to dismantle those lies and false beliefs and tell the truth about ourselves and the people around us. Integrity comes from letting go of blame and embracing our own capability.
So there are no demons, although there are things in the world we do not yet understand. We don't always like what we do, particularly when our actions don't line up with what we claim to believe. Still, we are responsible for all of our actions, even the ones about which we aren't happy. We are responsible for our beliefs, too. We don't have to believe things that reinforce the idea that we are weaklings or victims. Such beliefs hinder us from being all that we can be in the world, and such beliefs keep us from seeing other people clearly. It makes sense to believe in what's real. People are incredible. The world is amazing. If we start there, our journey will be infinitely more satisfying.